The basisphenoids are ventrally overlaid, and FIG.
In most birds the feet of the coracoids do not touch each other; in some groups they meet, in others one overlaps the other, the right lying ventrally upon the left.
In the region of the neck lateral strands pass through the transverse canal of the cervical vertebrae; but from the thoracic region onwards, where the cardiac branch to the heart is given off, each strand is double and the basal ganglia are successively connected with the next by a branch which runs ventrally over the capitulum of the rib, and by another which passes directly through the foramen or space formed between capitulum and tuberculum.
In the pelvic region, from about the level of the posterior end of the ischiadic plexus, the strand of each side becomes single again, passing ventrally over the transverse processes.
The hard fore-wings (elytra) are strengthened with marginal ridges, usually inflected ventrally to form epipleura which fit accurately along the edges of the abdomen.
Ten segments can be distinguished in the tapering abdomen, the ninth frequently bearing a pair of tail-feelers (cerci), and the tenth, attached ventrally to the ninth, having the anal opening at its extremity and performing the function of a posterior limb, supporting and temporarily fixing the tail end of the insect on the surface over which it crawls.
The anterior opening, the mouth, is situated ventrally, close to the tip of the head and in front of the brain in the Metanemertini, somewhat more backward and behind the brain in the other Nemertines.
Nected ventrally to the oeso phagus by a short vessel which supplies these tentacles in the immediate neighbourhood of the mouth.
Like the chief armnerve, this strand runs through the lophophore, parallel indeed with the former except near the middle line, where it passes ventrally to the oesophagus.
Ventrally forming an oblique X to XIII, The four pulmoniferous diaphragm, cutting off the somites.
In the adult there is a pair of such glands opening ventrally on the hindmost thoracic segment, or at the base of the abdomen; but in the young insect the glands are situated dorsally and open to the exterior on a variable number of the abdominal terga.
In most Ploima the dorsal gap is not well marked, and the trochus is broken up into a number of lobes, often furnished with vibratile styles, in front and at the sides, but ventrally passing into the uniformly ciliated oral funnel.
The largest is placed ventrally at some distance distal to the mouth.
- One row of branchial filaments is directed dorsally, the other ventrally; the mantle has a long posteroventral suture and a single posterior aperture; the labial palps of each side are fused together; shell elongate; hinge without teeth; periostracum thick.
Order Filibranchia Gill-filament ventrally directed and reflected, connected by ciliated junctions.
Mesodesmatidae.-External gill-plate directed ventrally; siphons separate and equal.
Mactridae.-External gill-plate directed ventrally; siphons united, invested by a chitinous sheath; foot long, bent at an angle, without byssus.
Both head and trunk are somewhat flattened dorso-ventrally, giving the insects a very distinct and characteristic aspect.
The rest of the body consists of the foot ventrally and the visceral mass dorsally.
In almost all Crustacea the food-canal runs straight through the body, except at its anterior end, where it curves downwards to the ventrally-placed mouth.
The right and left margins of the mantle are united ventrally, leaving an anterior and posterior aperture to the mantle cavity.
The dorsal surface is smooth; ventrally there are five pairs of parapodia, armed with supporting and hooked setae, by means of which the worm adheres to its host.
Into this same cloacal chamber open ventrally a pair of ciliated tubes communicating by funnels with the coelom (Nansen and Wheeler); these are possibly nephridia, and excretory in function.
The head carries three pairs of appendages, a pair of simple eyes, and a ventrally placed mouth.
Ventrally by a median opening?.
The jaw somite also disappears; the oral papilla somite forms ventrally the salivary glands, which are thus serially homologous with nephridia.
P. 115), has a bilobed carapace, ventrally open; Dendrogaster astericola, Knipovitch (Biologisches Centralblatt, 1891, x.