2918 



SHARKS AND RAYS 



upper Cretaceous. At the present day the family is represented by three genera, 

 each with but few species, from the warmer seas; and there are likewise certain ex- 

 tinct generic types. 



THE ELECTRIC RAYS Family TORPEDINIDJB, 



In common with the electric eel, the members of this family are characterized 

 by their power of communicating galvanic shocks; the organs from which this 

 power is derived taking the form of a series of vertically-placed prisms, situated on 



COMMON SKATE AND MARBLED ELECTRIC RAY. 

 (One-fifteenth natural size.) 



each side of the front of the disc between the head and the pectoral fins. In addi- 

 tion to this distinctive feature, these rays are characterized by the broad and smooth 

 disc, in which the rays of the pectoral fins do not extend in advance of the base of 



