The Anatomy of Chlamydoselachus 411 



into the cloaca. Hawkes (1907) states that, in two specimens studied by her, the rectal 

 gland opens into the rectum. It is so shown in her diagrammatic figure of the female 

 cloacal region reproduced as Text-figure 90a, p. 435). The function of the rectal gland 

 is unknown. 



In Heptanchus (Daniel, 1934) the portion of the digestive tube between the valvular 

 intestine and the anus is divided into two parts, colon and rectum. The two parts are 

 much alike, but the form of the colon is slightly bulbous. The duct of the rectal gland 

 reaches the wall of the rectum at its cephalic end, but does not enter here; it courses 

 cephalad in the wall of the colon to enter the lumen at the caudal end of the valvular 

 intestine. 



THE DIGESTIVE TUBE AS A WHOLE 



We have seen that the digestive tube of Chlamydoselachus is but slightly longer 

 than the body cavity, and that all its parts, save only the valvular intestine, are more or 

 less flaccid when empty. This leaves some doubt as to the precise form of the tube in 

 its natural position, both when empty and when distended with food. In all my speci' 

 mens the digestive tube is empty. In specimen No. I, which has a well'developed pyloric 

 vestibule, there is an abrupt S'shaped fold of the pyloric vestibule and related portion 

 of the cardiac stomach, in what appears to be the natural position of these organs. In 

 specimen No. II, which has a shorter pyloric vestibule, the smaller fold in the same region 

 cannot be straightened out. There are no other folds that appear to be of a permanent 

 nature, but in all my specimens there is considerable irregular folding in the walls of the 

 cardiac stomach. The question arises whether the distention of this organ with food 

 would be sufficient to take up whatever "slack" exists in this region. 



Table I gives the total length of the digestive tube, also the length of the body 

 cavity excluding the small portions along the sides of the cloaca, in my three specimens. 

 In specimen No. I the digestive tube is 100 mm. longer than the body cavity; in No. II 

 it is 105 mm. longer; in No. Ill it is 203 mm. longer. In No. I and in No. Ill the recurrent 

 course of the pyloric vestibule takes care of a small part of the excess length. It is probable 

 that, in specimens I and II, when the cardiac stomach was fully distended with food the 

 digestive tube became approximately straight; but the same statement could hardly 

 apply to specimen No. III. 



Giinther (1887) writes of Chlamydoselachus: "The stomach is an extremely long 

 cylindrical sack with thin walls ; the short and narrow intestine, after having made a short 

 and incomplete convolution, passes into the dilated portion which contains the spiral 

 valve." I have found no evidence of folding of the intestine in any of my specimens, and 

 it seems possible that the "short and incomplete convolution" mentioned by Giinther 

 really belonged to a pyloric vestibule. CoUett (1897) states that the intestinal canal of 

 his specimen is almost straight throughout its length, only the short duodenum being 

 turned aside between the pylorus and the dilated portion with the spiral valve. Deinega's 

 half-tone reproduction (1925, Fig. 1) of a drawing of the viscera in situ is printed on 



