How to use Posterior in a sentence
Limbs very slender; posterior nearly twice the length of the anterior.
This so-called third, upper or posterior conch is not a true conch, nor is that of the vestibulum; only the middle one forms a scroll, and this corresponds to the only one of reptiles and the lower of the mammals.
Thus the postcaval vein of the higher vertebrata is partly a new structure altogether, and is partly formed out of the pre-existing posterior cardinals.
The nervous system is thus essentially epidermal in position and diffuse in distribution; but an interesting concentration of nerve-cells and fibres has taken place in the collar-region, where a medullary tube, closed in from the outside, opens in front and behind by anterior and posterior neuropores.
Mark's narratives of the sepulture by Joseph of Arirathea and of the empty tomb are taken as posterior to St Paul; the narratives of the infancy in Matthew and Luke as later still.Advertisement
Of these divisions of the coelom the first two communicate with the exterior by means of a pair of ciliated pore-canals placed at the posterior end of their respective segments.
The proboscis-gut occurs as an outgrowth from the anterior dorsal wall of the collar-gut, and extends forward into the basal (posterior) region of the proboscis, through the neck into the proboscis-coelom, ending blindly in front.
In the neck of the proboscis the fibrous layer is greatly thickened, and other intensifications of this layer occur in the dorsal and ventral middle lines of the trunk extending to the posterior end of the body.
The dorsal epidermal nerve-tract is continued in front into the ventral wall of the collar nerve-tube, and at the point of junction there is a circular commissural thickening following the posterior rim of the collar and affording a special connexion between the dorsal and ventral nervetracts.
Without attempting to answer this question categorically, it may be pointed out that within the limits of the family (Ptychoderidae) which is especially characterized by their presence there are some species in Y art dY YY cts, posterior limit of collar.Advertisement
In the Trimerellidae, for example, some of the muscles are attached to a massive or vaulted platform situated in the medio-longitudinal region of the posterior half or umbonal portion of both valves.
The body of the Brachiopod v usually occupies about the posterior half of the space within the shell.
The intestine is slung by a median dorsal and ventral mesentery which divides the body cavity into two symmetrically shaped halves; it is " stayed " by two transverse septa, the anterior or gastroparietal band running from the stomach to the body wall and the posterior or ileoparietal band running from the intestine to the body wall.
In Rhynchonella, where there are two pairs of kidneys, the internal opening of the anterior pair is supported by the gastroparietal band and that of the posterior pair by the ileoparietal band.
It is a remarkable fact that in Discinisca, although the vessels to the lophophore are arranged as in other Brachiopods, no trace of a heart or of the posterior vessels has as yet been discovered.Advertisement
They are distinguished by having one of the five blue or yellow coloured sepals (the posterior one) in the form of a helmet; hence the English name monkshood.
The tergites of this region and those of the following region, the metasoma, are fused to form a second or posterior carapace in Limulus, whilst remaining free in Scorpio.
The y are really excretory glands, and communicate with the exterior by a very minute aperture on the posterior face of the coxa of the fifth limb on each side.
The scorpion's entosternite gives rise to outgrowths, besides the great posterior flaps, pf, which form the diaphragm, unrepresented in Limulus.
But most important of the evidences presented by the trilobites of affinity with Limulus, and therefore with the Arachnida, is the tendency less marked in some, strongly carried out in others, to form a pygidial or telsonic shield - a fusion of the posterior somites of the body, which is precisely identical in character with the metasomatic carapace of Limulus.Advertisement
On the other hand, it may well be doubted whether the pygidial or posterior carapace is primarily due to a fusion of the tergites of somites which were previously movable and well developed.
There is also a pair of narrow tergal sclerites interposed between the anterior and posterior shields.
Between the bases of the prosomatic limbs an anterior III and a posterior sternal plate (black) are seen.
In front of it the narrow waist is formed by the soft sternal area of the praegenital somite; 2, the sternite of the 2 second opisthosomatic somite covering the posterior pair of lung-sacs; and 4, the spinning appendages (limbs) of the opisthosoma; a, inner, b, outer ramus of the appendage; I I, sternite of the eleventh --
The posterior pulmonary sacs (except in Hypochilus) replaced by tracheal tubes; the anterior and posterior pairs replaced by tracheal tubes in the Caponiidae.Advertisement
Remaining pairs of appendages with their basal segments immovably fixed to the sternal surface, similar in form, the posterior three pairs furnished with two claws supported on long stalks; the basal segments of the 6th pair bearing five pairs of tactile sensory organs or malleoli.
The lower jaw projects more or less beyond the upper, the mental barble is small, sometimes rudimentary, the vent is below the posterior half of the first dorsal fin, and there is a dark spot in the axil of the pectoral fin.
The latter again are divided into Metanopsilae (in which the metanotum or posterior region of the thorax is bare) and Metanotrichae (in which the metanoturn is clothed with bristles or scales).
The anterior and posterior ends of the body are well defined.
The chief genital pore is placed anteriorly between the oral sucker and the ventral one, and is posterior only in Holostomidae, Gasterostomidae and a few Distomidae.
The large posterior organ of attachment is usually wheel-shaped and provided with hooks; but the ridges may become separated 'FIG.
A, Dorsal view showing the nervous system and digestive system; a, mouth; b, pharynx; c, d, e, gut; E, post-genital union of two limbs of gut; f, excretory pore; g, vaginal pore; h, j, k, brain and nerves; 1, dorsal nerves; m, ventral nerves; n, adoral sucker; o, posterior sucker; p, hooks on posterior sucker; r, vitello-intestinal duct.
The excretory system is highly developed and opens at the posterior extremity by a paired muscular bladder.
It is posterior (Amphistomidae), or anterior (Gasterostomidae).
They may be characterized as very elongated reptiles without limbs (unless with tiny vestiges of posterior limbs), without eyelids and external ear openings, with the teeth anchylosed to the supporting bones, a bifid slender tongue which is telescoped into its basal half, and with a transverse vent.
In some all the teeth are nearly of the same size; others possess in front of the jaws (Lycodonts) or behind in the maxillaries (Diacrasterians) a tooth more or less con spicuously larger than the rest; whilst others again are distinguished by this larger posterior tooth being grooved along its outer face.
One or more of the posterior maxillary teeth are grooved.
Characterized by possessing only a few teeth, on the posterior part of the maxillaries, on the palatines and Coronelline Nymphophidium, the same effect is reached by two prominences at the base of the skull.
In the latter case the larva crawls about the bottom of the water or up the stems of plants, with its thickly-chitinized head and legs protruding from the larger orifice, while it maintains a secure hold of the silk lining of the tube by means of a pair of strong hooks at the posterior end of its soft defenceless abdomen.
The anterior pair reach far beyond the end of the abdomen; the posterior are narrower and not so long.
No 1 Internally there Is a great difference in the form of the posterior margin of the sternum, as long ago remarked by Nitzsch.
The sexes are not distinct, the sexual organs being represented by a pair of testes and a single ovary, which open together into the posterior end of the alimentary canal.
According to the ordinary laws of research, the book, being written at a time long posterior to the events it records, can have only a secondary value, although that is no reason why here and there valuable material should not have been preserved.
The posterior end of the organ is positive, the anterior negative, and the current, passes from the tail to the head.
This version is quoted as Syr H (and when necessary Syr Hc* or Syr H mg) and by Tischendorf as SyrP (= Syra posterior).
The pallial line, which is the line of attachment of the mantle parallel to the edge of the shell, is not indented by a sinus at the posterior end.
The foot has a byssus gland on its posterior surface.
The tongue is generally beset with more or less scaly or velvety papillae and has always a well-marked posterior margin, while the anterior portion may or may not be more or less retractile into the posterior part.
This appendage is merely a fold of the skin, ornamental and sexual; it has no cavity in its interior, and has no communication with the mouth or with the respiratory organs; it is supported by the posterior horns of the hyoid bone, and can be erected and spread at the will of the animal.
It presents a single pair of muscles attached along its inner wall which run up and form a muscular girdle round the body in its posterior third.
The posterolateral angles of the gena are commonly produced into spiniform processes, which may project backwards beyond the middle of the body as in Paradoxides, or considerably beyond its posterior termination as in Trinucleus or Ampyx.
In the majority of Trilobites this groove passes backwards from the anterior or anterolateral edge of this plate to its posterior or postero-lateral border, dividing it into an inner portion continuous with the flabellum and fused tergal regions, and an outer portion bearing the eye.
Those genera, like Paradoxides, Olenus, Asaphus, Phillipsia and others, in which this groove cuts the posterior edge of the head-shield on the inner side of its angle are referred to the Opisthoparia; those, like Dalmanites and Phacops, in which it cuts the lateral border in front of the posterior angle, belong to the Proparia.
But in certain genera, like Conocoryphe, Calymmene and Triarthrus, it cuts the margin of the head-shield so close to the posterior angle that the distinction between the two groups practically breaks down.
In all other Trypanosomes there is only one flagellum, which is invariably attached to the body in the same manner as the posterior one of biflagellate forms. This flagellum, however, is most probably not to be considered homologous in all cases.
The point of insertion of the attached (posterior) flagellum into the body, and, consequently, the commencement of the undulating membrane may be almost anywhere in the anterior half of the body, but is usually near the extremity.
The crown of the third molar is nearly as long as those of the first and second together, having, in addition to the four principal lobes, a large posterior heel, composed of clustered conical cusps, and supported by additional roots.
The milk-dentition, and even the early condition of the permanent dentition, is formed on the same general type as that of Sus, except that certain teeth are absent, the formula being 13 i cl, total 34; but as age advances all the teeth have a tendency to disappear, except the canines and the posterior molars, but these, which in some cases are the only teeth left in the jaws, attain an extraordinary development.
The lower canines are much more slender, but follow the same curve; except on the posterior surface, their crowns are covered with enamel; both pairs of canines are large in the two sexes.
When hardened in situ its shape is that of a right-angled, triangular prism showing five surfaces - superior, anterior, inferior, posterior and right lateral which represents the base of the prism.
At its posterior margin the peritoneum of the great sac is reflected on to the diaphragm to form the anterior layer of the coronary ligament.
Again starting from the right side, two impressions are seen; the anterior one is for the hepatic flexure of the colon, and the posterior for the upper part of the right kidney.
The posterior boundary of the quadrate lobe is the transverse fissure, which is little more than an inch long and more than half an inch wide.
The posterior or attached border is uppermost.
The chief points in which they vary are - (1) in the structure of the ctenidia or branchial plates; (2) in the presence of one or of two chief muscles, the fibres of which run across the animal's body from one valve of the shell to the other (adductors); (3) in the greater or less elaboration of the posterior portion of the mantle-skirt so as to form a pair of tubes, by one of which water is introduced into the sub-pallial chamber, whilst by the other it is expelled; (4) in the perfect or deficient symmetry of the two valves of the shell and the connected soft parts, as compared with one another; (5) in the development of the foot as a disk-like crawling organ (Arca, Nucula, Pectunculus, Trigonia, Lepton, Galeomma), as a simple plough-like or tongueshaped organ (Unionidae, &c.), as a re-curved saltatory organ (Cardium, &c.), as a long burrowing cylinder (Solenidae, &c.), or its partial (Mytilacea) or even complete abortion (Ostraeacea).
It is the approximate equality in the size of the anterior and posterior adductor muscles which led to the name Isomya for the group to which Anodonta belongs.
In fact all Lamellibranchs begin with a condition in which there is only one adductor, and that not the posterior but the anterior.
Then the posterior adductor develops, and becomes equal to the anterior, and finally in some cases the anterior becomes smaller or disappears.
Their appearance and position suggest that they are in some way related morphologically to the gill-plates, the anterior labial tentacle being a continuation of the outer gill-plate, and the posterior a continuation of the inner gill-plate.
B,Diagram of the posterior face of a single complete filament with descending ramus and ascending ramus ending in a hook-like process;ep.,ep.,the ciliated junctions; il,j ., inter-lamellar junction.
Hind region of foot in Ano- Region altogether posterior to the foot in Anodonta.
Posteriorly beneath the posterior adductors, and covered only by a thin layer of elongated epidermal cells, are the visceral ganglia.
Formerly the posterior pair of ganglia were identified as simply the osphradial ganglia, and the anterior pair as the cerebral, pleural and visceral ganglia united into a single pair.
Anodonta has no eyes of any sort, and the tentacles on the mantle edge are limited to its posterior border.
After the formation of the gastrula by epibole the larva becomes enclosed by an ectodermic test covering the whole of the original surface of the body, including the shell-gland, and leaving only a small opening at the posterior end in which the stomodaeum and proctodaeum are formed.
The test is really a ciliated velum developed in the normal position at the apical pole but reflected backwards in such a way as to cover the original ectoderm except at the posterior end.
In Yoldia and Nucula proxima the ova are set free in the water and the test-larvae are free-swimming, but in Nucula delphinodonta the female forms a thin-walled egg-case of mucus attached to the posterior end of the shell and in communication with the pallial chamber; in this case the eggs develop and the test-larva is enclosed.
Symmetrical; mantle open throughout its extent; generally with well developed anterior and posterior adductors.
Parallelodontidae.-Shell as in Arca, but the posterior hinge teeth elongated and parallel to the cardinal border.
Lyrodesmidae.-Extinct; shell inequilateral, posterior side shorter; hinge short, teeth in form of a fan.
Megalodontidae.-Shell 1a, tr, Upper and lower inequilateral, thick; posterior siphons adductor impression on a myo ms, Siphonal muscle of the phorous apophysis.
An Aristotelian work often goes on continuously at first, and then becomes disappointing by suddenly introducing discussions which break the connexion or are even inconsistent with the beginning; as in the Posterior Analytics, which, after developing a theory of demonstration from necessary principles, suddenly makes the admission, which is also the main theory of science in the Metaphysics, that demonstration is about either the necessary or the contingent, from principles either necessary or contingent, only not accidental.
He got so far as gradually to write short discourses and long treatises, which we, not he, now arrange in the order of the Categories or names; the De Interpretatione on propositions; the Analytics, Prior on syllogism, Posterior on scientific syllogism; the Topics on dialectical syllogism; the Sophistici Elenchi on eristical or sophistical syllogism; and, except that he had hardly a logic of induction, he covered the ground.
The upper half or body of the uterus is somewhat triangular with its base upward, and has an anterior surface which is moderately flat, and a posterior convex.
The canal of the cervix is about an inch long, and is spindle-shaped when looked at from in front; its anterior and posterior walls are in contact, and its lining mucous membrane is raised into a pattern which, from its likeness to a cypress twig, is called the arbor vitae.
The vagina is a dilatable muscular passage, lined with mucous membrane, which leads from the uterus to the external generative organs; its direction is, from the uterus, downward and forward, and its anterior and posterior walls are in contact, so that in a horizontal section it appears as a transverse slit.
Owing to the fact that the neck of the uterus enters the vagina from in front, the anterior wall of that tube is only about 21 in., while the posterior is 31.
Posterior superior iliac spine Ureter Great sciatic notch Vas deferens; Spine of ischium Vas deferens Seminal vesicle Bladder wall Levator ani Prostate 9, ?
It is often described as formed of three lobes two lateral and a median or posterior, but careful sections and recent research throw doubt on the existence of the last.
When it is slit open from in front a longitudinal ridge is seen in its posterior wall, which is called the verumontanum or crista urethra, and on each side of this is a longitudinal depression, the prostatic sinus, into which numerous ducts of the prostate open, though some of them open on to the antero-lateral surface.
In the primitive condition there is one on each side in the mantle cavity, towards the posterior end of the body.
Thus in the primitive mollusc the mantle-cavity contains a symmetrical group of structures at the posterior end of the body, and this group of structures is called the pallial complex.
The heart is situated in the pericardium on the dorsal side of the intestine and at the posterior end of the animal.
The mouth is divided into two cavities communicating by a narrow orifice, the anterior one containing the incisors and the posterior the molars, the hairy skin of the face being continued inwards behind the incisors.
Riggs, is the unusual development of the premolar to the exclusion of the posterior teeth.
In Pelargonium the flower is zygomorphic with a spurred posterior sepal and the petals differing in size or shape.
The upper incisors have persistent pulps, and are curved longitudinally, forming a semicircle as in rodents; they are, however, not flattened from before backwards as in that order, but prismatic, with an antero-external, an anterointernal and a posterior surface, the first two only being covered with enamel; their tips are consequently not chisel-shaped, but sharp-pointed.
In this case also the posterior end of the larva represents the anterior end of the ant.
The wings are transparent and are black-bordered and black-barred, the anterior wing having two black bars and the posterior one.
Narrowing of the posterior portions of the spider's cephalothorax and sometimes of the anterior end of the abdomen reproduces the slender waist of the ant, and frequently transverse bands of hairs represent the segmentation of this region in the insect.
The mimicry of these insects therefore is synaposematic; but some, at all events, of the flies like the Bombylid Exoprosopa umbrosa, probably form pseudaposematic elements in the group. Into another category Hymenoptera enter not as models but as mimics, the models being inedible Malacodermatous beetles mostly belonging to the genus Lycus and characterized by orange coloration set off by a large black patch upon the posterior end of the elytra and a smaller black spot upon the thorax.
The anterior margin of each valve except the first is provided with two projections called sutural laminae which underlie the posterior margin of the preceding valve.
The series of gills may extend the whole length of the body in the pallial groove, or may be confined to the posterior end.
Each gill has the structure of a typical molluscan ctenidium, consisting of an axis bearing an anterior and posterior row of filaments or lamellae.
Both the openings are close together, the external opening being just in front of the principal gill near the posterior end of the body.
A simple gonaduct on each side arises from the gonad near its posterior end and passes first forwards, then backwards, and lastly outwards to the external opening in the pallial groove, anterior to the renal aperture.
There is also in some genera a median retractile sensory papilla on the dorsal posterior surface above the rectum, not covered by the cuticle.
The body chamber (reduced pallial chamber, conis worm-like and cylindritaining the concealed_pair of ctenidia) cal, the posterior half a to the right.
The chief difference is that the gonad or generative portion of the coelom is single and median, opening into the pericardium by a single posterior aperture.
In the Siebengebirge the little crater of Roderberg, with its lavas and scoriae of leucite-basalt, is posterior to some of the Pleistocene river deposits.
Histriodrilus resembles Saccocirrus in the possession of two posterior adhesive processes, and to some extent in the structure of the complex genital organs, which, however, are restricted to a single segment.
The limbs of the U are further twisted together in a looser or tighter coil, the axis of which may be traversed by a "spindle" muscle arising from the posterior end of the body.
There is a welldeveloped brain dorsal, to the mouth; this gives off a pair of oesophageal commissures, which surround the oesophagus and unite in a median ventral nerve-cord which runs between the longitudinal muscles to the posterior end of the body.
The posterior nares or choanae open far behind in the roof of the mouth, in recent forms within the pterygoids.
Dorsally the posterior nares open into this cavity.
It is of course written in Greek, and consists of parts of the substance of the Codex and the Digest, thrown together and often altered in expression, together with some matter from the Novels and imperial ordinances posterior to Justinian.
In the first it is a biconvex lens, from which segments are continually cut off parallel to the posterior surface; and in the second an elongated dome, from which segments are cut off by a transverse wall.
The thallus is somewhat spherical and unicellular, exhibiting a distinction between anterior and posterior extremities, and dorsal and ventral surfaces.
The most noteworthy point of distinction is in the skull, in which the facial portion is sharply bent down on the posterior basal axis in the fashion characteristic of the hollow-horned ruminants (oxen, antelopes, &c.), and the American prongbuck, instead of running more or less nearly parallel to the same, as in deer.
Above the brow-tine is developed a second palmated tine, which appears to represent the bez-tine of the red-deer; there is no trez-tine, but some distance above the bez the beam is suddenly bent forward to form an "elbow," on the posterior side of which is usually a short back-tine; above the back-tine the beam is continued for some distance to terminate in a large expansion or palmation.
The male is distinguishable from the female by the presence of a fork at the posterior end of the body.
The preacetabular portion of the ilium is shorter than the posterior half.
The hind-limb is typically avine, with intertarsal joint, distally reduced fibula, and the three elongated metatarsals which show already considerable anchylosis; reduction of the toes to four, with 2, 3, 4 and 5 phalanges; the hallux is separate, and as usual in recent birds posterior in position.
On literary-historical grounds the Pentateuch in its present form is post-exilic, posterior to the old monarchies and to the ideals of the earlier prophetical writings.
Genesis - Kings (incomplete; some further material in Jeremiah) and the later Chronicles - Nehemiah are in their present form posterior to Nehemiah's time.
The great commentaries exist only for the Posterior Analytics, Physics, De Caelo, De Anima and Metaphysics.
In the Posterior Analytics the syllogism is brought into decisive connexion with the real by being set within a system in which its function is that of material implication Posterior from principles which are primary, immediate and Analytics.
Thus to Aristotle the a priori argument is from law or cause to effect, as opposed to what we call a posteriori (posterior, subsequent, derived), from effect to cause.
In Ireland, Sir William Wilde has assigned their range approximately to the period between the 9th and 16th centuries; while Dr Munro holds that the vast majority of them, both in Ireland and in Scotland, were not only inhabited, but constructed during the Iron Age, and that their period of greatest development was as far posterior to Roman civilization as that of the Swiss Pfahlbauten was anterior to it.
The back of the body is occupied by a crest, called the dorsal fin, consisting of a hollow ridge, the cavity of which is divided into about 250 compartments or fin chambers, into each of which, with the exception of those near the anterior and posterior end of the body, projects a stout pillar composed of characteristic laminar tissue, the fin ray.
New clefts continue to form at the posterior end of the pharynx during the adult life of the animal.
At the level of its posterior end a pair of funnel-shaped pouches of the atrium are produced forwards into the dorsal coelom.
It is the central nervous system, and contains within itself the elements of the brain and spinal marrow of higher forms. The neurochord tapers towards its posterior end, where it is coextensive with the notochord, but ends abruptly in front, some distance behind the tip of the snout.
An important fact to note is that the blastopore is included in this overgrowth of epiblast, so that the neural tube remains for some time in open communication with the archenteron by means of a posterior neurenteric canal.
It is thus possible that the neurenteric canal is due to the conjunction of a posterior neuropore with the blastopore, i.e.
There is a strongly marked median longitudinal ventral black stripe, to which the lower ends of the transverse side stripes are usually united, but the dorsal stripe (also strongly marked) is completely isolated in its posterior half, and the uppermost of the broad haunch stripes runs nearly parallel to it.
These include works on the Physica, the Prior and the Posterior Analytics, the Meteorologica, the De anima, the De generatione animalium, the De generatione et interitu and the Metaphysica.
The organization of the oyster, as compared with that of a typical lamellibranch such as Anodon, is brought about by the reduction of the anterior part of the body accompanying the loss of the anterior adductor, and the enlargement of the posterior region.
After escaping from the genital aperture they find their way into the infra-branchial part of the mantle cavity of the parent, probably by passing through the suprabranchial chamber to the posterior extremity of the gills, and then being conducted by the inhalent current caused by the cilia of the gills into the infra-branchial chamber.
In Macropus giganteus and its immediate allies, the premolars and sometimes the first molar are shed, so that in old examples only the two posterior molars and the incisors are found in place.
Rezek, Gindely and others have dealt with the history of Bohemia posterior to the year 1526.
Other editions were printed from other versions, all evidently posterior to the original.
The fresh-water Mussels, Anodonta cygnea, Unio pictorum, and Unio margaritiferus belong to the order Eulamellibranchia of Lamellibranch Molluscs, in which the anterior and posterior adductor muscles are equally developed.
In most Decapods the " stomach " or dilated portion of the fore-gut is divided into two chambers, a large anterior " cardiac " and a smaller posterior " pyloric."
The blastopore generally occupies a position corresponding to the posterior end of the body.
In the region of the trunk, in many cases, paired mesoblastic bands are formed, growing in length by the division of teloblastic cells at the posterior end, and becoming segmented into somites.
The appendages posterior to the mandibles appear as buds on the ventral surface of the somites, and in the most primitive cases they become differentiated, like the somites which bear them, in regular order from before backwards.
At the same time, the tendency to a retardation in the development of the posterior thoracic somites is very general in Malacostracan larvae, and may perhaps be correlated with the f
The right and left margins of the mantle are united ventrally, leaving an anterior and posterior aperture to the mantle cavity.
The shell is narrower at the posterior end and is slightly curved to the dorsal side.
The edge of the mantle at the anterior aperture is very thick and muscular; at the posterior aperture also there is a circular muscle, and here the edge is interrupted by a ventral sinus and is provided internally with a dorsal and ventral valve which can be applied to each other so as to close the aperture.
The living animal buries itself in the sand with only the posterior extremity projecting into the Siphonopodiidae.
The gastrula thus formed has a large blastopore, which is at first posterior but afterwards gradually moves towards the anterior end of the ventral surface.
Shell curved with greatest diameter at anterior aperture and diminishing gradually to posterior.
The posterior margin of the wing is made to rotate, during the down stroke, in a direction from above downwards and from behind forwards - the anterior margin travelling in an opposite direction and reciprocating.
During the up or return stroke, on the other hand, the posterior margin rotates in a direction from below upwards and from before backwards, so that by a similar but reverse screwing motion the pinion attacks the air from beneath.".
The wing of the bird, like that of the insect, is concavo-convex, and more or less twisted upon itself when extended, so that the anterior or thick margin of the pinion presents a different degree of curvature to that of the posterior or thin margin.
The wing, during its vibrations, rotates upon two separate centres, the tip rotating round the root of the wing as an axis (short axis of wing), the posterior margin rotating around FIG.
The twisting referred to is partly a vital and partly a mechanical act; - that is, it is occasioned in part by the action of the muscles and in part by the greater resistance experienced from the air by the tip and posterior margin of the wing as compared with the root and anterior margin, - the resistance experienced by the tip and posterior margin causing them to reverse always subsequently to the root and anterior margin, which has the effect of throwing the anterior and posterior margins of the wing into figure-of-8 curves, as shown at figs.
The different parts of the wing, moreover, travel at different degrees of velocity - the tip and posterior margin of the wing always rushing through a much greater space, in a given time, than the root and anterior margin.
One naturally inquires why the high speed of wings, and why the progressive increase of speed at their tips and posterior margins?
Whether, therefore, the air strikes the wings from below, or the wings strike the air from above, the result is the same, - the posterior or flexible margins of the wings yield in an upward direction, and in so doing urge the bird in a horizontal direction."
That the posterior margin of the wing yields to a slight extent during both the down and up strokes will readily be admitted, alike because of the very delicate and highly elastic properties of the posterior margins of the wing, and because of the comparatively great force employed in its propulsion; but that it does not yield to the extent stated by Marey is a matter of absolute certainty.
If any one watches the horizontal or upward flight of a large bird he will observe that the posterior or flexible margin of the wing never rises during the down stroke to a perceptible extent, so that the under surface of the wing, as a whole, never looks backwards.
He describes two artificial wings, the one composed of a rigid rod and sail - the rod representing the stiff anterior margin of the wing; the sail, which is made of paper bordered with cardboard, the flexible posterior margin.
It is of a more or less triangular form, thick at the root and anterior margin, and thin at the tip and posterior margin.
The twisting is most marked at the tip and posterior margin, particularly that half of the posterior margin next the tip. The wing when in action may be divided into two portions by a line running diagonally between the tip of the wing anteriorly and the root of the wing posteriorly.
The tip and posterior parts of the wing are more active than the root and anterior parts, from the fact that the tip and posterior parts (the wing is an eccentric) always travel through greater spaces, in a given time, than the root and anterior parts.
It is not possible to determine with exactitude the precise function discharged by each part of the wing, but experiment tends to show that the tip of the wing elevates, the posterior margin propels, and the root sustains.
India-rubber springs were made to extend between the inner posterior parts of the wings and the frame, corresponding to the backbone of the bird.
In what has been called, though erroneously, as we shall see, Confucius's History of his own Times, we find only 13 states of note, and the number of all the states, large and small, which can be brought together from it, and the much more extensive supplement to it by Tso K`iu-ming, not much posterior to the sage, is under 150.
On the other, posterior, side of the grain is a more or less evident, sometimes punctiform, sometimes elongated or linear mark, the hilum, the place where the ovule was fastened to the wall of the ovary.
The anterior wings, when present, are always small; but the posterior wings are sometimes of large size and very beautifully coloured.
Lastly, he showed, both from theoretical considerations and from the result of actual experiment on the living animal, that the anterior roots of the spinal nerves are motor, while the posterior are sensory.
The posterior cavities were the largest, but what had become of their original opening to the exterior is uncertain.
The remains of the original genital gland within the theca became the "axial organ" surrounded by the "axial sinus" derived from the anterior coelom, and this again by structures derived from the right posterior coelom, which, as explained above, had been depressed to the aboral pole.
Both the milk and the permanent dentition display the aforesaid complexity of the hinder teeth as compared with those in front, and since the number of milk-teeth is always considerably less than that of the permanent set, it follows that the hinder milkteeth are usually more complex than the teeth of which they are the predecessors in the permanent series, and represent functionally, not their immediate successors, but those more posterior permanent teeth which have no direct predecessors.
Those of each jaw are placed in continuous series without intervals between them; and, although the anterior teeth are simple and single-rooted, and the posterior teeth complex and with several roots, the transition between the two kinds is gradual.
When there is a marked difference between the premolars and molars of the permanent dentition, the first milk-molar resembles a premolar, while the last has the characters of the posterior molar.
In the floor of the mouth, between the two branches of the lower jaw, and supported behind by the hyoid apparatus, lies the tongue, an organ the free surface of which, especially in its posterior part, is devoted to the sense of taste, but which by reason of its great mobility (being composed almost entirely of muscular fibres) performs important mechanical functions connected with masticating and procuring food.
They may have rudimentary exopodites, and may or may not have branchial filaments or lamellae developed on their posterior faces.
A character of great diagnostic value in the more primitive Arachnida is the tendency of the chitinous investment of the tergal surface of the telson to unite during growth with that of the free somites in front of it, so as to form a pygidial shield or posterior carapace, often comprising as many as fifteen somites (Trilobites, Limulus).
The form of the ear depends on the relative width of the anterior and posterior surfaces as compared with that of the lateral surfaces.
Schliemann was on several occasions in England, in 1883 to receive honours from the great universities, and in 1886 to confute, at a special gathering of the Hellenic Society, the assertion of Stillman and Penrose that the Tirynthian palace was posterior to the Christian era.
This view of the surfaces is, however, disputed by De Selys-Longchamps, who regards the aboral extremity of the adult as the posterior end.
On the contrary, he tries to prove elaborately that they (as well as the pleasures of imagination, ambition, self-interest) cannot be made an object of primary pursuit without a loss of happiness on the whole - one of his arguments being that these pleasures occur earlier in time, and " that which is prior in the order of nature is always less perfect than that which is posterior."
All the rays through a given point in the first principal focal plane of the anterior system of lenses traverse the plate as a parallel beam and reunite at the corresponding point of the second focal plane of the posterior system, each in its passage being divided into two by the plate having a given relative retardation.
The latter sends a horizontal or slightly ascending process backwards below the orbit to join the under surface of the zygomatic process of the squamosal, which is remarkably large, and instead of ending as usual behind the orbit, runs forwards to join the greatly developed post-orbital process of the frontal, and even forms part of the posterior and inferior boundary of the orbit, an arrangement not met with in other mammals.
This consists mainly of a long and compressed stylohyal, expanded at the upper end, where it sends off a triangular posterior process.
A strong ligamentous band behind the metapodium, arising from near the upper extremity of its posterior surface, divides into two at its lower end, and each division, being first connected with one of the paired upper sesamoid bones, passes by the side of the first phalanx to join the extensor tendon of the phalanges.
Its upper extremity embraces the lower surface of the cartilaginous ear-conch; its lower end reaches the level of the inferior margin of the mandible, along the posterior margin of which it is placed.
Its posterior end rests against the anterior surface of the transverse process of the atlas, from which it extends forwards and downwards, slightly curved, to beneath the ramus of the jaw.
Each segment is again divided by lateral fissures, which do not extend quite to the posterior border of the organ; of the central lobes thus cut off, the right is rather the larger, and has two fissures in its free border dividing it into lobules.
The Spigelian lobe is represented by a flat surface between the postal fissure and the posterior border, not distinctly marked off from the left lateral by a fissure of the ductus venosus, as this vessel is buried deep in the hepatic substance, but the caudate lobe is distinct and tongue-shaped, its free apex reaching nearly to the border of the right lateral lobe.
The buccal cavity, as explained above, is a secondary formation around the true mouth, which is at its dursal posterior end.
A and feet with two primary papillae on the anterior side and one on the posterior side; outer jaw with one minor tooth at the base of the main tooth, inner jaw with no interval between the large tooth and the series of small ones; last fully developed leg of the male with enlarged crural gland opening on a large papilla placed on its ventral surface; coxal organs absent; the nephridial openings of the 4th and 5th pairs of legs are placed in the proximal spinous pad.
A variable number of posterior legs of the males anterior to the genital opening with one or two large papillae carrying the openings of the crural glands; well-developed coxal organs present on most of the legs.
With 23 to 25 pairs of claw-bearing legs, four spinous pads on the legs, and nephridial openings of legs 4 and 5 in the middle of the proximal pad or on its proximal side; feet with two primary papillae, one anterior and one posterior; outer jaw with two, inner jaw with two or three minor teeth at the base of the main tooth, separated by a diastema from the row of small teeth; crural glands present in the male only, in the two pairs of legs preceding the generative opening; coxal glands present.
In the order Scrophulariaceae one of the two carpels is posterior and the other anterior, whilst in Convolvulaceae the carpels are arranged laterally.
The symmetry in the flower is evidently dimerous, and the abnormality in the androecium, where the four long stamens are opposite the posterior sepals, takes place by a splitting, at a very early stage of development, of a single outgrowth into two.
The upper lip is often composed of three parts, which are thus posterior or next the axis, while the lower has two, which are anterior.
The anterior antennae are fused with the anchoring attachment, whilst the posterior pair is vestigial, and the appendages of the mouth and body present various degrees of degeneration and specialization.
In the Caudata and Apoda, cartilage often persists between the vertebrae; this cartilage may become imperfectly separated into a cup-and-ball portion, the cup belonging to the posterior end of the vertebra.
Howes (39), dealing with the azygous (posterior) cardinal veins in salamanders and some of the Ecaudata.
He saw that the second part of Isaiah differs from the first not only in style but in date; that the grammar and the history of the Pentateuch are posterior to the time of Moses; that the book of Daniel is clearly apocryphal.
Diagram to illustrate parathyroid anatomy (posterior view) - click to enlarge There is variation in the number and location of glands.
Most of the displacement is usually anterior, and the posterior capsule is not significantly disrupted.
Cerebellum - occupies most of the posterior cranial fossa; damage produces ataxia, slurring of speech.
The Istanbul team studied a group of 40 subjects suffering from chronic posterior blepharitis.
The posterior column is then stabilized by lag screws placed along the pelvic brim.
The doctor aims the laser exactly onto the posterior lens capsule in order to cut away a small circle shaped area.
The anterior commissure is shown in red, and the posterior commissure in yellow.
The highest point of the iliac crest in this position is slightly posterior to the gravity line.
A combined posterior medial displacement calcaneal osteotomy and Evans osteotomy was used, with transfer of FDL to the medial cuneiform and TA lengthening.
In the high bar method, the bar will be resting on top of the posterior deltoids right at the base of the neck.
Granulomas in the hypothalamus or posterior pituitary can cause diabetes insipidus.
X-rays of the elbow were taken which show a posterior dislocation.
The third region is located in the right dorsal (posterior) frontal cortex (bottom lateral view of brain ).
The phylum Chytridiomycota has traditionally been characterized on the basis of motile cells with a single posterior flagellum.
A region of posterior left middle temporal gyrus showed significantly increased activation for verbs.
Logged Torn ACL, stable, medial meniscus tear of posterior horn.
The peritoneal reflection is then incised with the diathermy a few millimeters posterior to the " white line " .
Then do a single foot tiptoe test to look for tibialis posterior insufficiency.
Cruciate ligament reconstruction may alleviate the anterior knee pain associated with anterior or posterior cruciate ligament laxity.
Other posterior segment complications included macular edema (four) and epiretinal membrane involving the macula (two ).
The significance a fracture of the posterior malleolus is controversial.
There is no difference in the reported clinical results of medial displacement posterior calcaneal osteotomy and lateral column lengthening.
Dorsal Stream Occipital cortex to posterior parietal and frontal lobes.
The posterior parietal lobes are responsible for achieving this for you.
Nerve impulses from the hypothalamus stimulate the posterior pituitary to produce ADH when the osmotic pressure of the blood rises.
Cells from part of the brain grow downwards to form the posterior pituitary.
In a recent survey, eDiets got the bottom line on bottoms and asked which famous face has the most appealing posterior!
Take a front/back (anterior posterior) X-ray to ascertain whether the problem is in the left or right or both lungs.
Bass is primal, and it reminds me of a large posterior - but both spirituality and sexuality originate higher up in the body.
The full conditional densities are evaluated and inverted numerically to obtain random draws of the joint posterior.
The esophagus also begins at this level and lies directly posterior to the trachea.
Do you think that Freya was in the occiput posterior position, which would explain why your labor didn't progress faster?
In mammals, it is located in the anterior part of the visceral cavity, just posterior to the diaphragm.
What conclusions do you draw from the computation of the posterior probability?
The posterior primary ramus then divides into 3 branches - medial, intermediate and lateral.
Anatomy The posterior tibial nerve runs just behind the inside ankle bone in a tunnel covered by the flexor retinaculum.
For example, external tibial rotation that occurs in response to a posterior force is called a coupled external rotation.
This throwing movement involves the external shoulder rotators (the posterior shoulder muscles) and the arm extensors (the triceps ).
Table 1 illustrates these differences for the test and control brushes for the anterior and posterior sextants of the mandible and maxilla.
The instability may also be noticed on external rotatory movements which cause posterior subluxation of the lateral tibial plateau.
Analysis of MRI scans of confirmed vCJD patients revealed high signal in the posterior thalamus (pulvinar ).
Typically unilateral, posterior headache that can be precipitated mechanically.
There is also flow of contrast into the posterior urethra up into bladder cavity.
This is to determine the role of ionizing radiation in the treatment of clinical posterior uveitis.
Accordingly Aquinas prepared himself on this side by commentaries on Aristotle's De Inter pretatione, on his Posterior Analytics, on the Metaphysics, the Physics, the De Anima, and on Aristotle's other psychological and physical writings, each commentary having for its aim to lay hold of the material and grasp the method contained and employed in each treatise.
Their transverse dorsal connexion is the posterior commissure; otherwise the whole roof portion of the midbrain is reduced to a thin membrane, continuous with that which covers the Sylvian aqueduct, and this ventricle sends a lateral cavity into each optic lobe, as is the case in reptiles.
In a large number of Diptera an incision in the posterior margin of the wing, near the base, marks off a small lobe, the posterior lobe or alula, while connected with this but situated on the thorax itself there is a pair of membranous scales, or squamae, which when present serve to conceal the halteres.
In Autolytus there is, to begin with, a conversion of the posterior half of the body to form a sexual zooid.
The conversion of the posterior end of the simple individual into a sexual region is dispensed with; but from a preanal budding segment a series of sexual buds are produced.
Shell with medium spire, external or partly covered by the mantle; genital aperture below the right posterior tentacle; genital apparatus generally provided with a dart-sac and multifid vesicles.
It is evident that the features of the sternum of which De Blainville chiefly relied were those drawn from its posterior margin, which no very extensive experience of specimens is needed to show are of comparatively slight value; for the number of " echancrures - notches as they have sometimes been called in English - when they exist, goes but a very short way as a guide, and is so variable in some very natural groups as to be even in that shot way occasionally misleading.
The-considerations are not very striking from a general point of view; but the author adds to the weight of evidence which some of his predecessors had brought to bear on certain matters, particularly in aiding to abolish the artificial groups " Deodactyls," "Syndactyls," and " Zygodactyls," on which so much reliance had been placed by many of his countrymen; and it is with him a great merit that he was the first apparently to recognize publicly that characters drawn from the posterior part of the sternum, and particularly from the " echancrures," commonly called in English " notches " or " emarginations," are of comparatively little importance, since their number is apt to vary in forms that are most closely allied, and even in species that are usually associated in the same genus or unquestionably belong to the same family, 2 while these " notches " sometimes become simple foramina, as in certain pigeons, or on the other hand foramina may exceptionally change to " notches," and not unfrequently disappear wholly.
The posterior ends of the palatals and anterior of the pterygoids articulate directly with the rostrum.
The posterior median process with its repetition of triangular segments closely resembles the same process in Limulus.
It has been compared with the canal of Laurer of Trematodes (the vitello-intestinal duct of the ectoparasitic flukes), but if we take the more primitive Cestodes, and especially Aniphilina, into consideration we find that they possess, in addition to the uterus, an anterior vagina (usually present in Cestodes) and a posterior one.
In the Cestodes the vagina is present (V); the canal of Laurer (LC) is now vestigial (present in Caryophyllaeus as the posterior vagina).
The left anterior tentacle (seen in the figure) is joined at its base in front of the mouth (w) to the right anterior tentacle, and similarly the left (o) and right posterior tentacles are joined behind the mouth.
Aviculidae.-Shell very inequilateral; cardinal border straight with two auriculae, the posterior the longer.
The anterior part of the penis is formed by the glans, a bell-shaped structure, apparently continuous with the corpus spongiosum, and having the conical ends of the corpora cavernosa fitted into depressions on its posterior surface.
Beneath the anterior parts of the radula where it emerges from the caecum are a pair of cartilages, and attached to these a number of special muscles by which the radula is moved backwards and forwards to act as a rasp. The secretion of the radula at the closed end of the caecum is continuous, so that it is constantly growing forward as fast as its exposed anterior portion is worn away by use, just as a fingernail is pushed forward by constant growth at its posterior end, and is worn away or has to be cut short from time to time at its outer end.
Squirrels of this and the' other arboreal groups have the bodily form slender and agile, the tail long and bushy, the ears well developed, pointed and often tufted; the feet adapted for 1 ' climbing, the anterior pair with four toes and a rudimentary thumb, and the posterior pair with five toes, all the toes having long, curved and short-pointed claws (see Squirrel).
The organization of the oyster, as compared with that of a typical lamellibranch such as Anodon (see Lamellibranchia), is brought about by the reduction of the anterior part of the body accompanying the loss of the anterior adductor, and the enlargement of the posterior region.
In this stage of existence the elongated upper part of the larynx projects into the posterior nares, and so maintains a free communication between the lungs and the external surface, independently of the mouth and gullet, thus averting danger of suffocation while the milk is passing down the gullet.
The opponents of the book rely (1) on the testimony of a certain Louis Guyon, who in 1604 declared that the fifth book was made long after Rabelais's death by an author whom he knew, and who was not a doctor, and on the assertion of the bibliographer Du Verdier, about the same time, that it was written by an "ecolier de Valence"; (2) on the fact that the anti-monastic and even anti-Catholic polemic is much more accentuated in it; (3) on the arguments that parts are apparently replicas or rough drafts of passages already appearing in the four earlier books; and (4) that some allusions are manifestly posterior to even the furthest date which can be assigned for the reputed author's decease.
As development proceeds, the body of the nauplius elongates, and indications of segmentation begin to appear in its posterior part.
The wing is so constructed that the posterior margin yields freely in a downward direction during the up stroke, while it yields comparatively little in an upward direction during the down stroke; and this is a distinguishing feature, as the wing is thus made to fold and elude the air more or less completely during the up stroke, whereas it is made to expand and seize the air with avidity during the down stroke.
A plane passing through the anterior and posterior sepal and through the floral axis is termed the median plane of the flower; a plane cutting it at right angles, and passing through the lateral sepals, is the lateral plane; whilst the planes which bisect the ?? ?
This throwing movement involves the external shoulder rotators (the posterior shoulder muscles) and the arm extensors (the triceps).
The roughened aspiration tip can be used for reliable selective polishing of the posterior capsule.
A posterior saccular aneurysm may not be so obvious.
The amount of ADH secreted by the posterior pituitary is determined by sensors in the brain which monitor the concentration of the blood.
Keeping the needle horizontal, advance posterior to the clavicle aiming for the sternal notch.
A V-shaped line, the sulcus terminalis, divides the tongue into an anterior 2/3 and a posterior 1/3.
The presence of the posterior interosseous nerve in the substance of the supinator muscle is of paramount importance.
Analysis of MRI scans of confirmed vCJD patients revealed high signal in the posterior thalamus (pulvinar).
For repeat injuries, however, a posterior splint may be applied for several days.
Selective dorsal rhizotomy surgery, also called selective posterior rhizotomy, involves a surgical resection of part of the spinal nerve.
This gland is divided into the anterior (front) and posterior (back) halves.
Another area of the brain that appears to be linked to phobias is the posterior cerebellum.
There are 12 sets of bilateral cranial nerves originating in the posterior portion of the brain stem, called the pons.
The differential diagnosis and treatment of posterior plagiocephaly is a challenging aspect of craniofacial surgery.
Patients with high myopia, greater than 6.00 diopters, have an increased risk of developing a retinal tear, hole, or detachment; a posterior staphyloma; a posterior vitreous detachment; or glaucoma.
Posterior nosebleeds, which come from the back of the nose, are less common and much harder to manage.
Tangas typically leave the full posterior of the wearer completely exposed, and with that kind of definition, it's easy to see why it made the list of the top ten sexiest swimwear styles.
Shorts, by their very nature, put the focus squarely on your posterior, so you'll want to make sure you pay a bit more attention to that area of your body before you hit the beach.
Note too that boy shorts will inevitably draw the eye to your posterior, so you may want to do a few lunges and side squats to help you feel more confident and to show your body in its best light.
There are three parts of the deltoid - anterior (front), posterior (back) and lateral (side).
Wish you had a bit more padding to your posterior?
First two premolars with compressed and sharp-pointed crowns, and slightly developed anterior and posterior accessory basal cusps.
In relation to their parasitic habit one or two suckers are always developed, the one at the anterior and the other at the posterior end of the body.
They frequently progress after the fashion of a "looper" caterpillar, attaching themselves alternately by the anterior and the posterior sucker.
The posterior, so-called processus Zygomaticus is very variable; in many Galli it encloses a foramen by distally joining the orbital process.
Then follows the rib-bearing portion and then the processus lateralis posterior; this also is the product of ribs, consequently the right and left processes together are equivalent to the xiphoid process or xiphisternum of the mammals.
The median and posterior extension of the body of the sternum is a direct outgrowth of the latter, therefore FIG.
One of these, broad and fleshy, is inserted upon the posterior surface of the distal third of the femur.
The gonads are, moreover, limited and fixed in numbers, and are practically invariably attached to the intersegmental septa, usually to the front septum of a segment, more rarely to the posterior septum.
The heart is usually posterior to the branchia (proso-branchiate).
This columella muscle is the same thing as the muscles adhering to the shell in Patella, and the posterior adductor of Lamellibranchs.
The heart c lying in the pericardium is seen in close proximity to the renal organ, and consists of a single auricle receiving blood from the gill, and of a single ventricle which pumps it through the body by an anterior and posterior aorta.
Mantle with two posterior appendages; ctenidium large and capable of protrusion from pallial cavity.
Foot divided into two, posterior half bearing the operculum; a wide epipodial velum; shell turbinated.
Visceral sac and shell coiled in one plane; foot divided transversely into two parts, posterior part bearing an operculum, anterior part forming a fin provided with a sucker.
Foot with anterior transverse groove; a posterior pallial tentacle; generally burrowing.
Its superficial extent is seen when the folds covering the shell are cut away and the shell removed; the external surface forms a triangle with its base bordering the pericardium, and its apex directed posteriorly and reaching to the lefthand posterior corner of the shell-chamber.
On examination this is found to be the under surface of the posterior limb of the gland, the upper surface of which has just been described as lying beneath the shell.
When the pericardium is cut open from above in an animal otherwise entire, the anterior face of the kidney is seen forming the posterior wall of the pericardial chamber; on the deep edge of this face, a little to the left of the attachment of the auricle to the floor of the pericardium, is seen a depression; this depression contains the opening from the pericardium into the kidney.
Thus the base of the gill passes in a slanting direction across the right-hand side of the kidney, the posterior end being dorsal to the apex of the gland, and the anterior end ventral to the right-hand corner.
Posterior cephalic tentacle; and b, the eyes.
Cephalic shield continuous with neck; twelve to fourteen stomachal plates; a posterior pallial filament passing through a notch in shell.
Pulmonata with two pairs of tentacles, except Janellidae and Vertigo; these tentacles are invaginable, and the eyes are borne on the summits of the posterior pair.
A relation between objects of art described by Homer and the Mycenaean treasure was generally allowed, and a correct opinion prevailed that, while certainly posterior, the civilization of the Iliad was reminiscent of the Mycenaean.
Below each eye is a cheek area (gena), often divided into an anterior and a posterior part, while a distinct chin-sclerite (gula) is often developed behind the mouth.
Carriere's researches (1897) on the make its appearance simultaneously throughout the whole length of embryology of the mason bee (Chalicodoma) agree entirely with the the plate; the anterior parts are segmented before the posterior.
He finds that the endoderm arises may be readily distinguished, six of which subsequently enter into from an anterior and a posterior rudiment derived from the " endothe formation of the head, three going to the thorax and twelve to blast," that many of the cells of these rudiments wander into the the abdomen.
Comstock and C. Kochi believe that the labrum belongs to it,, The appendages of the posterior three or trophal segments become the parts of the mouth.
From these facts it appears that the anterior three divisions of the head differ strongly from the posterior three, which greatly resemble thoracic segments; hence it has been thought possible that the anterior divisions may represent a primitive head, to which three segments and their leg-like appendages were subsequently added to form the head as it now exists.
But the latter used this privilege wisely and well-not, after the manner of De Blainville and others subsequent to him, relying solely or even chiefly on the character afforded by the posterior portion of the sternum, but taking also into consideration those of the anterior, as well as of the in some cases still more important characters presented by the pre-sternal bones, such as the furcula, coracoids and scapulae.
These nine theoretical centres or " pieces " L'Herminier deemed to be disposed in three transverse series (rangees), namely the anterior or " prosternal," the middle or " mesosternal " and the posterior or " metasternal " - each series consisting of three portions, one median piece and two side-pieces.
As to the third or posterior series, when it is complete the three constituent pieces are developed almost simultaneously; but its median piece is said often to originate in two, which soon unite, especially when the side-pieces are wanting.
In the Gallinae the five well-known pieces or centres of ossification are said to consist of the two side-pieces of the second or middle series, and the three of the posterior.
At the same time he states that authors who have occupied themselves with the sternum alone have often produced uncertain results, especially when they have neglected its anterior for its posterior part; for in truth every bone of the skeleton ought to be studied in all its details.
In them the vomer, however variable, always tapers to a point anteriorly, while behind it includes the basisphenoidal rostrum between the palatals; but neither these nor the pterygoids are borne by its posterior divergent ends.
The Chanson de Roland, which cannot be posterior to the First Crusade - for the poem never alludes to it - already contains the idea of the Holy War against Islam.
In the posterior retractor the longitudinal fibres become united into one bundle, which, as noticed above, is inserted in the wall of the sheath.
The proboscis broken off and expelled is generally reproduced, the posterior ribbon-like end of this reproduced portion again fusing with the walls of the sheath.
There is reason to suppose that, when a wound is inflicted by the central stylet, it is envenomed by the fluid secreted in the posterior proboscidian region being at the same time expelled.
In the posterior portion this epithelium in certain Heteronemertea has a more glandular appearance, and sometimes the interior cavity is obliterated by cell-proliferation in this region.