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TEXTBOOK OF ZOOLOGY 



Order Batoidei — Skates and Rays. — This is a group of depressed or 

 dorsoventrally flattened fishes in which the gill slits are located on 

 the broad, flat, ventral side. "These fish lack the anal fin and the 

 caudal is absent or reduced. The saw-fish, Pristis pectinatus is a 

 sharklike ray with a long tooth-bearing rostral process or snout that 

 resembles a double-edged saw. These animals may reach a length of 

 fifteen or twenty feet, with a saw five feet in length. 



The skates are distributed along our Atlantic shores and are ovip- 

 arous. The eggs are enclosed in dark brown cases or capsules, 

 quadrate in outline and of considerable size. They have hornlike 

 processes extending from each corner. There are about six species 

 of skates, of which Raja erinacea, B. diaphanes, and B. ackleyi are 

 common ones. 



Fig. 229. — Butterfly ray, a common bottom feeder. 



The rays are of similar shape, but they bear their young alive and 

 tend to have a smoother skin. The rays are more numerous in the 

 warmer waters. The torpedo ray of family Torpedinidae, has at- 

 tracted considerable attention because of its ability to generate and 

 store electrical energy in the muscles of the bases of the broad pec- 

 toral fins. These electric organs are capable of discharging suffi- 

 cient current to paralyze other animals, ring a doorbell, or light a 



