THE BEAKED RAYS 



2915 



of their tails. The tooth-like tubercles on the skin frequently attain a great devel- 

 opment, and are aggregated into prominent bosses or longitudinal ridges. Dr. 

 Giinther writes that the mode of life of these fishes is quite in accordance with the 



THORNBACK SKATES. 

 (One-sixteenth natural size.) 



form of their body, the true rays leading a sedentary life, moving slowly on the bot- 

 tom of the sea, and rarely ascending to the surface. Their tail has almost entirely 

 lost the function of an organ of locomotion, acting in some merely as a rudder. 



