The Anatomy of Chlamydoselachus 



337 



zation may affect the body form in either of 

 two ways : the body may become short and 

 broad, as in skates, frogs and turtles; or it 

 may become very slender, as in eels, coecil' 

 ians and snakes. A consideration of the 

 evidence upon which this generaliziation is 

 based would take us too far afield, but it is 

 a principle that appears to be accepted by 

 most comparative anatomists. 



In the case of Chlaynydoselachus, the 

 elongation of the body has proceeded far 

 enough to remove it from the category of 

 primitive characters. It serves, perhaps, as 

 an adaptation to life on a rough sea bottom, 

 where the animal is obliged, occasionally, to 

 swim or crawl through crevices. In such 

 situations, Chlamydoselachus may lie in hid' 

 ing, or may even stalk its prey, then strike 

 suddenly as does a snake. But there is another 

 advantage to be gained from an elongate 

 form of body. It may be observed that the 



ectoparasitic cyclostomes have bodies that are very slender, and that Echeyieis 

 sucking fish, also is slender'bodied. These are creatures that fasten on to fishes larger than 

 themselves and are towed along by the host. Owing to the slenderness of their bodies 

 they are not readily shaken off. Because of the large mouth and the prehensile teeth 

 (Text'figure 2), it has been surmised (Gudger and Smith, 1933) that Chlamydoselachus 

 seizes and swallows Hving prey nearly as large as itself. The swallowing of a large fish 

 struggHng to escape is presumably not an easy matter, and were Chlamydoselachus a form 

 that offered much resistance to being dragged through the water, it might not be able to 

 maintain its initial hold. 



Text'figure 2. 

 Front view of the widely'distended mouth of 

 a specimen of Chlamydoselachus collected in 

 Japanese waters by Dr. Bashford Dean and 



presented to Columbia University. 



After Gudger and Smith, 1933, Fig. 3, pi. X. 



the 



Text'figure 3. 

 Heptanchus (Heptahranchias) maculatus, adult female. 



!AJ!A[, nares; SP, spiracle. 

 After Dean, 1895, Fig. 93. 



