1196 THE CETACEANS 



THE SPERM WHALE 

 Genus Physetet 



The sperm whale, or, as it is frequently called from its French title, cachalot 

 ( Physeter macrocephalus) , is one qf the largest of the Cetaceans, fully rivaling in 

 size the Greenland whale. As with many other species, its dimensions have, how- 

 ever, been considerably exaggerated; although, on the other hand, it is quite prob- 

 able that when the species was more abundant than at present, some individuals 

 attained a size which is now never reached. Be this as it may, the male sperm 

 whale is definitely known to attain a length from fifty-five to sixty feet; but 

 females are said not to reach much more than half these dimensions, while their 

 form is proportionately more slender. The essential generic characteristics of the 

 sperm whale are to be found in the great proportionate size of the head, which 

 equals about one-fourth of the total length of the animal, and in the number of 

 the teeth being from twenty to twenty-five on each side of the lower jaw. 



In appearance the sperm whale is ungainly and ugly in the extreme, 

 this being chiefly due to the great height and abrupt truncation of the 

 enormous muzzle, upon the summit of which is situated the S-shaped aperture of 



Form 



SKELETON OF SPERM WHALE. 



the nostrils, somewhat to the left of the middle line. The mouth, which is of great 

 length and capacity, opens below, and at some distance behind the extremity of the 

 muzzle. On the upper surface of the skull, as seen in our figure of the skeleton, is 

 a huge cavity, bounded behind by a tall vertical wall of bone; this cavity being 

 filled in the living animal with the substance known as spermaceti, of which more 

 anon. In front of this hollow protrudes the long rostrum of the upper jaw, the 

 gum of which contains rudimentary teeth. The lower jaw is very long and slender, 

 its two branches being united in the middle line for about half their total length. 

 The teeth are implanted in the lower jaw in a long groove, partially divided into 

 sockets by incomplete bony partitions. These teeth are of large size, and, when un- 

 worn, are pointed and recurved at their tips. They are composed solely of ivory, 

 and the pulp cavity at their base remains open for a long period, although generally 

 more or less completely closed in adult life, when the whole base of the tooth be- 

 comes much flattened from side to side. The tongue and interior of the mouth are of 

 a glistening white color, and the diameter of the throat is very large. The eye is 

 placed somewhat above the angle of the mouth, and a short distance behind it is the 

 minute aperture of the ear, which is said not to exceed a quarter of an inch in diameter. 



