384 CHAPTERS ON THE NATURAL HISTORY 



turn the same way, or the twist has the same direction. Nor- 

 whals feed upon small fish and crustaceans. 



Herring Hogs (Phocwna) are representatives of another very 

 interesting genus (Fig. 97) ; these animals are also known as the 

 Harbor porpoises or " puffing pigs " ; they have earned their last 

 name from their habit of puffing and grunting as they disport 

 themselves in the surf or as they roll in the breakers at the 

 mouths of harbors and rivers. These Herring hogs are very de- 

 structive of several species of the small edible fish, and of oys- 

 ters, but they in turn are often attacked and killed by the Por- 

 poises. 



To represent the next family, the Bottle-nose whales, I have 

 given a. figure of Hi/ pe rood on bidens. But very little is known of 

 these forms and the nomenclature of the group is not in a very 

 satisfactory condition. 



Fig. 94. The " Herring Hog " {Phocmna communis). 



Copied by the Author from a photograph by the U. S. Fish Commission. Length of adult, rather more 



than 4 feet. 



Passing next to the family of the true Sperm whales 

 (Physeteridce), we find them represented by the Giant Sperm and 

 the Pigmy Sperm whales. 



The Sperm whale or Cachalot (P. macrocephalus) is a very well- 

 known cetacean, one of wide distribution and of great commer- 

 cial importance (Fig. 98). In this species the male may attain the 

 enormous length of 84 feet, whereas the females are not more 

 than one-third as large, and are slenderer. In color these animals 

 are of a blackish brown above, paler on their sides, and grayish on 

 the under parts; very old ones are gray on top of the head and 

 about the nostrils. They feed on small fish principally, and 

 squids; it is related that several hundred maekeral have been 

 taken from the stomach of a third grown one. All times of the 

 year is the breeding season for them, and one at a birth is the 

 rule, never more than two. The female nurses her young by re- 



