GENERAL ZOOLOGY 



Fig. 18.10. Representative Chon- 

 drichthyes. A, shark and rays. B, 

 ventral aspect of a prickly skate; 

 note the separate and exposed gill 

 slits, characteristic of elasmo- 

 branchs. (A, photograph of a 

 museum group, courtesy Chicago 

 Natural History Museum; B, 

 photograph courtesy New York 

 Zoological Society.) 



survivors representing the earliest type of fishes, ahhough they are a highly 

 specialized and perhaps degenerate group. A lamprey feeds by attaching its 

 sucker-like mouth to the surface of another fish and abrading the flesh with its 

 inner mouth parts. The mouth is also used for holding to stones in swift 

 water. The hags likewise feed upon other fishes, becoming attached and 



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