CONTENTS 



Page 



Introduction 1 



Class Chondrichthyes, the cartilaginous fishes 2 



Sharks 4 



Skate s and rays 10 



Chimaeras 14 



Annotated list of references 16 



ILLUSTRATIONS 



"Family tree" of the vertebrates illustrating, in the opinion of many zo- 

 ologists, the relations existing among members of the group 2 



A great hammerhead from the Gulf of Mexico and her litter. Few sharks 



produce this many young at one time 4 



A "typical" shark, illustrating terms used in description 5 



Top: A small spiny dogfish shark, Squalus CubenSlS, from the Gulf of 

 Mexico. Many species of sharks are many times smaller than this 

 species. Bottom: A large silky shark, Eulamia floridana, taken on a 

 tuna longline. These large, oceanic sharks sometinries reach lengths 



of ab out lOfeet 6 



A small thresher shark, AlopiaS vulpinus. A 14-foot specimen of this 

 species, recently taken was estimated to weigh approximately 500 

 pounds and possessed a caudal lobe measuring 7^ feet. The long 



caudal lobe is apparently used to stun prey 9 



Removing the liver from a large silky shark 10 



A generalized skate illustrating terms used in description 11 



A "typical" ray, the roughtail stingray, Dasyatis centroura. This specimen 

 measured 62 inches across the fins and weighed 285 pounds. Such rays 

 are taken frequently in trawl drags along the east coast of the United 



State s 13 



A generalized chimaera illustrating terms used in description 14 



