Where locomotive appendages (the parapodia of the Polychaeta) exist, they are never jointed, as always in the Arthropoda; nor are they modified anteriorly to form jaws, as in that group.
Thus, in Octochaetus multiporus a large nephridium opens anteriorly into the buccal cavity, and numerous nephridia in the same worm evacuate their contents into the rectum.
The anteriorly-opening and usually very large nephridia are not uncommon, and have been termed "peptonephridia."
Associated with these glands are frequently to be found bundles or pairs of long and variously modified setae which are termed penial setae,to distinguish them from other setae sometimes but not always associated with rather similarglandswhich are found anteriorly to these, and often in the immediate neighbourhood of the spermathecae; the latter are spoken of as genital setae.
Helcion, circlet of branchiae interrupted anteriorly, British.
Scutum, mantle split anteriorly and reflected over shell, which has no slit.
Shell flattened, umbilicated; foot anteriorly truncated with angles produced into lobes.
Shell with numerous tuberculated whorls; aperture canaliculated anteriorly; short pallial siphon.
Shell turriculated and siphonated, thick, each whorl with varices; foot broad and truncated anteriorly; pallial siphon well developed; proboscis present.
Spengel's observation of the osphradium and its nervesupply in these forms; the nerve to that organ, which is placed somewhat anteriorly - on the dorsal surface - being given off from the hinder part (visceral) of the right compound ganglion - the fellow to that marked A in fig.
Cephalic disk enlarged anteriorly, forming an open tube posteriorly; shell external, thick, with p:ominent spire; no operculum.
The dorsal vessel is prolonged anteriorly into an aorta, through which the blood is propelled into the great After Miall and Denny, The Cockroach, Lovell body-cavity or haemoReeve & Co.
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 brain-lobes are generally four in number, a ventral and a dorsal pair, respectively united together by the above-mentioned commissures, and moreover anteriorly interfusing with each other, right and left.
Anteriorly there is a certain amount of difference in the arrangement.
Anteriorly it finally communicates with the lacunae just mentioned, which surround the oesophagus, bathe the posterior lobes of the brain, pass through the nerve ring together with the proboscidian sheath, and are generally continued in front of the brain as a lacunar space in the muscular tissue, one on each side.
Anteriorly this base supports a gurrie or gutter, the pre-oral rim of which is formed by a simple lip, but the post-oral rim is composed of a closely set row of tentacles.
Anteriorly the dorsal vessel splits into a right FIG.
9, A) or anteriorly only (Holostomidae).
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.
- Ectoparasitic Trematodes, in which a large posterior adhesive apparatus is present and is usually accompanied by a pair of suckers placed anteriorly in relation to the mouth.
Schistostomum (Bilharzia) haematobium in which the male is larger than the female and encloses the latter in a ventral canal; Koellikeria filicolle Rud (Distomum okenii, K01l) which also occurs in pairs, a large female and a small male being found together encysted in the branchial chamber of Brama raja: and Didymozoon thynni (Monostomum bipartitum) which occurs in pairs fused for the greater part of their length and only free anteriorly; the larger individual is the female.
Anteriorly these chords embrace the oesophagus and unite with the cerebral mass which innervates the pair of eyes when present.
More or less nearly related to the saiga is the chiru, Pantholops hodgsoni, of Tibet, characterized by the long upright black horns of the bucks, and the less convex nose, in which the nostrils open anteriorly instead of downwards.
The lampreys are readily recognized by their long, eel-like, scaleless body, terminating anteriorly in the circular, suctorial mouth characteristic of the whole sub-class.
The latter is further remarkable for having the median area of the head-shield, the flabellum, produced into an anteriorly directed spike.
The mouth lies in the median line anteriorly, the anus in the median line posteriorly.
The actual condition in Anodonta at the region where the gills begin anteriorly is shown in fig.
Limopsidae.-Shell orbicular, hinge curved, ligament longer transversely than antero-posteriorly; foot elongate, pointed anteriorly and posteriorly.
The clitoris is the representative of the penis, and consists of two corpora cavernosa which posteriorly diverge to form the crura clitoridis, and are attached to the ischium; the organ is about an inch and a half long, and ends anteriorly in a rudimentary glans which is covered by the junction of the labia minora; this junction forms the prepuce of the clitoris.
The middle lobe forms the alimentary canal; it closes behind and opens to the exterior anteriorly and so makes the mouth.
The upper ones are the largest, and are continuous anteriorly with the labial glands, the ducts of which open on the mucous membrane of the upper lip.
A long dorsal fln, high and pointed anteriorly, runs along nearly the whole length of the back; the caudal is strong and deeply cleft.
The following is Pettigrew's description of wings and wing movements published in 1867: " The wings of insects and birds are, as a rule, more or less triangular in shape, the base of the triangle being directed towards the body, its sides anteriorly and posteriorly.
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 head is situated on the dorsal side of the body anteriorly within the anterior aperture of the mantle, from which it cannot be protruded.
There is a single unsegmented nerve-cord which runs along the ventral middle line and enlarges posteriorly into a caudal ganglion and anteriorly in a ganglion, the brain, which is not supra-oesophageal.
The whole is anteriorly somewhat loosely slung to the skin, so as to allow free play when the animal is extending or retracting its introvert.
The largest pair of branchiae is placed immediately behind the renal openings and corresponds to the single pair of other molluscs, the organs being repeated anteriorly only (Metamacrobranchs) or anteriorly and posteriorly (Mesomacrobranchs).
The four cords are all connected anteriorly with the cerebral commissure which lies above the buccal mass anteriorly.
Into the groove open mucous glands, a large one anteriorly and another opening into a posteriorly cloacal, branchial cavity.
The pedal cords anteriorly form a pair of pedal ganglia united by a thick commissure.