92 On the genus Onchidium. [No. 2, 



portion of the liver (1). The intestines (i) issue somewhere at the 

 muscular bridge which connects the two portions of the stomach, 

 being from here in their entire length enveloped in the liver 

 which is readily recognised by the greenish colour of the hepatic cells. 

 The length of the intestines is from 4 — 5 inches, the rectum (r) being 

 much wider, and passing almost in a straight direction to the anus. 

 Near its termination it is accompanied by two whitish, dendritic organs, 

 (gp and pa), each of which at their posterior ends is connected with a 

 small yellowish brown gland. The latter may represent the kidneys, 

 and the former are probably only albuminous glands, or they may be 

 an equivalent organ of some of the pyloric appendages or the coecss. 

 The anus is situated at the end of the upper base of the foot, it is sur- 

 rounded by ring muscles, but externally very slightly thickened. 



Onchidium tgphce, and probably most of the other species live, on 

 decaying wood and earth, impregnated with organic matter. I have 

 never seen them feeding on fresh grasses. With the solid excrements 

 always a large portion of watery liquid is given out. 



Generative organs. 



All the species of Onchidia which I have examined are hermaphro- 

 dites, not as Buchannan stated in the case of O. typhce, supposing the 

 sexes to be distinct. The generative organ occupies the posterior half 

 of the internal cavity of the body (see fig. 2, pi. xiv), sometimes even 

 a little more. The hermaphrodite genital pore (g and v in fig. 5) lies 

 very close to tlie right of the anus ; in this pore a very strong, 

 almost cartilaginous tube, the oviduct, (or here the uterus, ov) termi- 

 nates, and a short distance upwards gives off a short branch, ending in a 

 flattened large vesicle, which usually is interpreted as the receptaculum 

 seminis (rs). The contents of this organ in numerous specimens 

 which I examined was a dark yellowish brown, rather watery sub- 

 stance, containing some solid bodies, resembling the spicula3 of Spongia, 

 or those peculiar arrows connected with the copulation of Helices. The 

 uterus which is only a continuation of the oviduct is, as stated above 

 a thick, white, doubly twisted string, near the middle it is partially 

 enveloped in a mucus secreting, foliated, pale orange gland (as in 

 fig. 2, pi. xiv.)* The contents of this gland is a simple granular 



* In figure 5 this gland lies to the right of the testis (t) and to the left of 

 the receptaculum seminis (rs). 



