474 MRS. O. A. aiERRITT HAWKES ON THE [May 28, 



7 pa«s forward, 1 is contorted, and 35 are directed backwards. In 

 all the species of Elasmobranchs which Parkei- (3) described there 

 was a much smaller number of coils which were [either directed 

 forwards or backwards continuously. He states, however (p. 49), 

 that " in a smaller specimen of the same species {Scyllium cmiictda), 

 there were 8 turns to the valve, of which 5 had a forward and the 

 last 3 a backward direction." This condition was exceptional in the 

 species named. It is not improbable that the twofold direction of 

 the valves in Chlamydoselachus has some physical relation to the 

 large number of coils. It can have no relation to the length of the 

 colon, as this is not relatively longer than in the majority of 

 Elasmobranchs. On the other hand, the twofold direction may 

 have a special physiological significance. Where the valves are 

 directed forward, the passage of the food is undoubtedly slower 

 than where they are directed backwards. 



In Chlamydoselachus the coils of the spiral valve are closer to 

 one another, and the valve is broader, in the anterior than in the 

 posterior region. The anterior valves are covered by numerous 

 well-defined strife. The valve reaches a breadth of three-fourths 

 of the diameter of the colon in the anterior region, which is, /)ar 

 excellence, the region of intestinal digestion. Owing to the anterior 

 direction of the valves, the movement of the food is slow, and it 

 is further hindered by the contorted coil which divides the colon 

 into two physiological parts. Absorption takes place in the 

 posterior part where the valves are directed backwards, and where 

 there is comparative rapidity of movement. In this region, the 

 stria? are absent, except on the first 7 coils where they are few and 

 inconspicuous. 



The spleen is interesting in that it is divided into two parts 

 wdiich are separated by a space of 4 cm. The additional lobe is 

 situated to the right of the stomach and somewhat dorsally. It 

 is an ovoid body, 3 cm. long and nearly 2 cm. broad in the widest 

 part, and is situated between the stomach and a fold of mesentery 

 which supports the latter. The other part or spleen proper lies 

 in the usual place at the angle of the stomach. The histological 

 characters of the spleen proper when examined by a low -power 

 lens present the usual appearace, but the structure of the additional 

 lobe is much more compact. 



The rectum has thin and much wrinkled walls. Its diameter 

 is slightly greater than that of the adjacent portion of the colon. 

 The rectal gland opens into the rectum in the mid-dorsal line, 

 1-5 cm. beyond the end of the colon. According to Giinther the 

 gland opens into the cloaca, but it certainly did not do so in the 

 two specimens examined by me. 



The liver consists of right, left, and median lobes. The gall- 

 bladder is situated in the median lobe. The length of the lobes 

 necessitates their being doubled forward upon themselves. In one 

 specimen, the end of the left lobe was lying on the right side of 

 the body-cavity. 



