REPORT OjST THE NUDIBRANCHIATA. 
127 
on either side is the strong cylindrical rhinophore (ophthalmophore), which is exsertile, 
and bears an eye on its outer end; at the sides the frontal shield is prolonged into a 
tentacle. In the middle hue, at the hinder end of the body, on the under surface of the 
mantle edge, generally at its base, is the pneumostome, the lung-aperture ; below this, and 
above or at the root of the short tail is the anus. Along the right side of the body 
runs the female genital furrow , which is ciliated during the life of the creature ; it com- 
mences in front of the anus, and is prolonged as far as the region of the opening of the 
so-called foot gland, which lies in the median line, above the anterior margin of the foot. 
At the hindermost extremity of this furrow lies the female genital opening ; the male 
aperture is at the upper side of the frontal shield, nearer the middle line or below the 
right rhinophore. The foot is large and generally broad. 
The central nervous system resembles that of other Pulmonates, as do the sense- 
organs ; the remarkable dorsal visual organs, proper to this group, are formed on the type 
of the vertebrate eye. — The bulbus pharyngeus and tongue are like those of other 
Pulmonates; jaw-like organs are found only exceptionally ( Onchidium boreale). There 
are three stomachs — an anterior, a masticatory, and a posterior (a kind of psalterium). 
The liver is also divided into three portions — an anterior (-upper), an inferior, and a 
posterior (-upper). The intestine is very long. The lung cavity is at the hinder end 
of the body, and extends to the right upwards ; it opens nearly always in the median 
line, through the short respiratory tube with its aperture (pneumostome). On the walls 
of the lung cavity is the renal organ, which appears to open within it close to the 
respiratory tube . 1 The pericardium lies in the body- wall. — The hermaphrodite gland 
is made up of two halves, and is of the usual structure. The hermaphrodite duct 
forms only a very small or no special ampulla. The anterior genital mass (mucous 
and albuminiparous glands) is short and more or less rounded. The vesicula seminalis 
is large, roundish, and opens at the base of the duct of the mucous gland ; this last duct 
opens within or at the hinder end of the female genital furrow. The vas deferens 
first takes its way along the mucous duct, and with it enters the side wall of the body, and 
then bends forward and becomes much thinner, and is enclosed within the body wall , 2 
1 V. Jhering has, as is well known, divided the order Pnlmonata (Vergl. Anat. d. Nervensyst. d. Moll., 1877, pp. 225- 
239, and Ueberdie system. Stell. von Peroniau. die Ordn. Nephropneusta, Jh., 1877) of Cuvier into two orders — the Nephro- 
pneusta ( Helicoidect ) and Branchiopneusta ( Limnoidea ). He agrees with Milne-Edwards (Leg. s. Ia phys. et l’anat. comp. t. 
ii., 1857, p. 91) in regarding the lung of the first-mentioned as morphologically the dilated termination of the renal organ 
(or cloaca) of the marine Ichnopoda ; and the lung of the second group as the equivalent of a branchial cavity, from 
which the bran chi re have disappeared. Semper (Einige Bemerk. rib. die Nephropneusten v. Jhering’s. Arb. aus dem 
zool. zoot. Inst, in Wiirzb., Bd. iii., 1877, pp. 480-488) has brought forward considerable evidence against this, which has 
hardly been weakened by a later work of v. Jehring’s (Ueber die system. Stellung von Peronia und die Nephropneusta, 
1877, pp. 30-32). 
2 Other Pulroonata show the same course of the vas deferens. In Veronicella ( Vaginulus ) the condition is similar, 
but the part imbedded in the musculature is shorter, because the place where the vas deferens is imbedded in the skin 
lies, together with the vulva, about the middle of the side, and not at its end, as in Onchidium. A similar condition is 
also found in the Auriculacea and Lynmseacea, in which also a portion of the vas deferens, but much shorter than in 
Onchidium, is imbedded in the body- wall. Cf. Semper, loc. cit., p. 251. 
