260 



A COURSE ON ZOOLOGY. 



is much smaller. It is gregarious, and many are often 

 seen swimming in file, their backs appearing alternately 



FIG. 201. 



COMMON DOLPHIN (Delphinusdelphis). 



above the water. Its teeth, like those of the dolphin, 

 are admirably adapted for catching fish. 



FIG. 202. 



PORPOISE (Phocaena communis). 



The cachalot, or sperm whale, grows as long as fifty or 

 sixty feet ; it has teeth only in the lower jaw. Its head 

 is enormous, forming one-third the length of the body. 



