PISCES 125 



twenty feet. They catch their prey by enveloping it in their great 

 "wings." They are true "sea-vampires," dreaded by pearl divers 

 near Panama, who are said to have been caught and drowned by these 

 great "winged" creatures. They are sometimes known as "devil 

 fishes." 



Saw-Fishes (Pristiidce) exhibit one of the most striking special- 

 izations seen among the Batoidei. In them the body (Fig. 68, B) is 

 only slightly broadened laterally, but the rostrum is prolonged until 

 it reaches a length half as great as the rest of the body. The rostrum is 

 armed with two lateral rows of knife-like teeth which enable the fish 

 to deal vicious slashing blows at its enemies. It is said that they at- 

 tack whales in the soft parts behind the flippers, tearing off and de- 

 vouring pieces of flesh. 



Order Holocephali (Chimeras) 



Chimseras (Fig. 69) are by some considered as a divergent offshoot 

 of the Elasmobranchii; by others they are placed in a distinct sub- 

 class of coordinate value with the whole sub-class Elasmobranchii. 

 It is difficult to decide between these two alternatives. There are 

 undoubtedly some characters that relate the Holocephali to the Elas- 

 mobranchii, but there are also some very fundamental differences. 

 They agree with the elasmobranchs in the following ways: a wholly 

 cartilaginous endoskeleton; no cartilage or membrane bones; the 

 limb girdles and the limb skeletons essentially elasmobranch in struc- 

 ture; the dermal denticles, present locally in some modern forms 

 and more generally in extinct forms, agree with those of elasmo- 

 branchs; the brain is very similar; the reproductive system, including 

 clasping organs in the male, and large chitinous-shelled eggs, remind 

 one strongly of the elasmobranchs; there is no air-bladder; there is a 

 spiral valve; there is a conus arteriosus; the nostrils are connected 

 with mouth by oro-nasal grooves. The group is undoubtedly one of 

 great antiquity and probably branched off from the elasmobranchs 

 of early times. The specialized features are: The skull is autostylic, 

 the jaw cartilage (palatoquadrate) being flrmly fused with the base of 

 the cranium, a character which accounts for the name (holos — ^whole 

 or undivided; cephalos — head). The teeth are modified into large 

 crushing dental plates. The claspers, instead of consisting merely of 

 one pair derived from the pelvic fins, are five in number. One pair 

 is like that of the elasmobranchs; a second pair occurs in pockets of 



