Pallial Sentence Examples
In these there are neither branchia nor osphradium, and the pallial chamber which retains its large open ing serves as a lung.
Cephalic shield continuous with neck; twelve to fourteen stomachal plates; a posterior pallial filament passing through a notch in shell.
Adult without shell; a sub-epithelial pseudoconch formed by connective tissue; pallial cavity ventral.
Shell not coiled, symmetrical; pallial cavity ventral.
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.Advertisement
The pallial cavity, with its organs, is by this torsion moved up the right side of the larva to the dorsal surface, and thus the left organs become right and vice versa.
In some cases each pleural ganglion is connected with the opposite branch of the visceral commissure by anastomosis with the pallial nerve, a condition which is called dialyneury; or there may be a direct connective from the pleural ganglion to the visceral ganglion of the opposite side, which is called zygoneury.
They are termed pallial gills.
In the latter a pallial siphon, a welldeveloped proboscis and an unpaired oesophageal gland are always present, in the former they are usually absent.
Pallial cavity transformed into a lung; pedal centres concentrated; a deep pedal groove.Advertisement
Mantle with two posterior appendages; ctenidium large and capable of protrusion from pallial cavity.
Shell turriculated and siphonated, thick, each whorl with varices; foot broad and truncated anteriorly; pallial siphon well developed; proboscis present.
Foot with anterior transverse groove; a posterior pallial tentacle; generally burrowing.
Where the modification is carried to its extreme degree, not only the shell but the pallial cavity, ctenidium and visceral hump disappear, and the body acquires a simple elongated form and a secondary external symmetry, as in Pterotrachaea and in Doris, Eolis, and other Nudibranchia.
The pallial cavity is always well developed, and contains the ctenidium, at least in part; ctenidium, except in Lophocercidae, of folded type.Advertisement
Posteriorly the mantle forms a large pallial lobe FIG.
Foot without parapodia; no pallial cavity, but always a single ctenidium situated on the right side between mantle and foot.
In both Oncidiidae and Pecten the pallial eyes have probably been developed by the modification of tentacles, such as coexist in an unmodified form with the eyes.
All have an osphradium, except the Auriculidae, which are terrestrial, and it is situated outside the pallial cavity in those forms in which water is not admitted into the lung.
Visceral mass and shell conical; tentacles atrophied; head expanded; genital apertures contiguous; marine animals, with an aquatic pallial cavity containing secondary branchial laminae.Advertisement
Visceral mass and shell conical; head flattened; pallial cavity aquatic, but without a branchia; genital apertures separated.
Visceral mass and shell sinistral; inferior pallial lobe very prominent, and transformed into a branchia.
When the edges of the mantle ventral to the inhalant orifice are united, an anterior aperture is left for the protrusion of the foot, and thus there are three pallial apertures altogether, and species in this condition are called " Tripora."
Such a subdivision of the pallial chamber, and direction of the currents set up within it do not exist in a number of Lamellibranchs which have the gill-lamellae comparatively free (Mytilus, Arca, Trigonia, &c.), and it is in these forms that FIG.17.
In the Arcidae the pallial eyes are compound or faceted somewhat like those of Arthropods.Advertisement
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.
Cycladidae.-One siphon or two free siphons with simple orifices; pallial line simple; hermaphrodite, embryos incubated in external gill-plate; freshwater, Cyclas; British.
Mutelidae.-Differs from Unionidae in having two pallial sutures; freshwater.
Mantle not extensively closed; two pallial sutures and two well developed siphons.
Two pallial sutures, siphons somewhat elongated and partially or wholly united.
Veneridae.-Foot well developed; pallial sinus shallow or absent.
Petricolidae.-Boring forms with a reduced foot; shell elongated, with deep pallial sinus.
Asymmetrical, inequivalve, fixed, with extensive pallial sutures; no siphons.
Shell with a pallial sinus; dorsal region protected by accessory plates.
The shell extends to the edge of the mantle-fold, and the cavity between the mantle and the side of the body is the pallial chamber.
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 ramifications of the arteries convey the blood to all parts of the body, and it finally reaches the venous sinuses, the chief of which are the pedal, the pallial and the median-ventral.
The pallial cords are united to one another posteriorly, dorsal to the rectum.
The ventral surface forms a flat creeping "foot," and between mantle and foot is a pallial groove in which there is on each side a series of gills.
These papillae form pallial sense-organs, I containing nerve-end bulbs, covered by a dome of cuticle, and innervated from the pallial nervecords.
The series of gills may extend the whole length of the body in the pallial groove, or may be confined to the posterior end.
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.
The venous blood is conducted from the tissues to a large sinus on either side above the pallial groove, and from this sinus passes to the gills by an afferent vessel in each gill on the internal or pedal margin of the axis.
The oxygenated blood is carried from each gill by an efferent vessel on the external or pallial side of the axis to another longitudinal vessel which leads to the auricle on each side.
The eggs may be laid separately invested by a chitinous envelope, or as in Ischnochiton magdalenensis they may form strings containing nearly 200,000 eggs, or the ova may be retained in the pallial groove and undergo development there, as in Chiton polii and Hemiarthrum setulosum.
The body chamber (reduced pallial chamber, conis worm-like and cylindritaining the concealed_pair of ctenidia) cal, the posterior half a to the right.
Heart and blood-vessels are entirely absent; the blood is contained in sinuses which have no distinct walls or endothelial lining, and the principal of which are the perianal, the pedal, the visceral and the pallial.
No ctenidium, pallial cavity transformed into a lung; aperture of shell circular; terrestrial.
Shell with numerous tuberculated whorls; aperture canaliculated anteriorly; short pallial siphon.
In the most primitive condition the genital duct is single throughout its length and has a single external aperture; it is therefore said to be monaulic. The hermaphrodite aperture is on the right side near the opening of the pallial cavity, and a ciliated groove conducts the spermatozoa to the penis, which is situated more anteriorly.
Shell ovoid, with short spire, wide aperture and folded columella; inferior pallial lobe thick; visceral commissure still twisted.
Visceral mass and shell sinistrally coiled; shell thin, with narrow aperture; no inferior pallial lobe.
In siphonate forms the pallial muscle is not simple, but is indented posteriorly by a sinus formed by the muscles which retract the siphons.
Pectinibranchia.-In this order there is no longer any trace of bilateral symmetry in the circulatory, respiratory and excretory organs, the topographically right half of the pallial complex having completely disappeared, except the right kidney, which is FIG.