224 Transaction*. — Zoology. 



of the posterior end of the stomach, and the whole alimentary canal appears 

 like an almost simple narrow tube greatly exceeded in calibre by the oviducts. 



The intestine has a well-marked duodenal section or bursa Entiana (b.e) 

 into the left lateral wall of which the stomach opens by a small pylorus 

 (py) guarded by a well-marked annular pyloric valve. The rest of the in- 

 testine is somewhat narrower than the stomach, and of tolerably uniform 

 diameter except at its posterior end, where it narrows considerably before 

 entering the cloaca ; with the dorsal wall of this posterior portion or rectum 

 (/•) is connected the large rectal gland (r. gl). 



The stomach is supported by a mesogaster attached along the anterior 

 two-thirds of its dorsal side : the intestine is free save for a mesorectum 

 attached to the rectal gland, and to the dorsal wall of the rectum posterior 

 to that structure. 



The spiral valve (sp.v) is the most perfect apparatus of the kind I 

 have yet examined. It belongs to what I have elsewhere* described as 

 " type C," that is, the width of the valve is greater than the semi-diameter 

 of the gut, and the plane of any part of it is inclined, from its attachment 

 to the intestinal wall, forwards or towards the duodenal end. There are 

 twenty- seven turns to the valve, the total length of the intestine being 

 inches. The muscular wall of the intestine (w) is greatly thickened, the 

 thickening being often especially well marked between the turns of the 

 spiral valve. Thus the absorbent surface of the mucous membrane is 

 further increased, an additional obstacle is offered to the passage of the 

 intestinal contents, and great muscular power is obtained for their propul- 

 sion towards the cloaca. This great development of the intestinal muscu- 

 lature is an exaggeration of what I described, in the paper just referred to, 

 in Scyllium canicula. 



The liver (fig. 1, Ir) is of immense size, its two lobes reaching quite to 

 the posterior end of the abdominal cavity ; it weighed 9 lbs. in the fresh 

 state. There is no gall-bladder ; the wide bile-duct (figs. 2 and 3, b. d) 

 passes from the liver in the gastro-hepatic omentum (fig. 1, g.h.o) to the 

 right side of the stomach, and then proceeds directly backwards to open 

 into the anterior wall of the bursa Entiana (fig, 2). 



The pancreas (figs. 1 and 2, pn) consists of two lobes : one (fig. 2, pn) 



closely applied to the ventral surface of the intestine, just beyond the bursa 



Entiana; the other [pn!) passing backwards and outwards to the left side of 



the spleen (spl), and surrounding the right mesenteric vein (r.m.v). The 



spleen (sjrt) is large, compact, scarcely at all lobulated, and very distensible, 



swelling to two or three times its orginal size when injected through the 



arteries. 



* On the Intestinal Spiral Valve in the genus Kaia," Trans. Zool. Soc, vol. xi., pt. 2, 

 1880, p. 49. 



