SPERM WHALES 363 



enormous head of the Cachalot and the very fairly -developed 

 skull of the "Pygmy Sperm Whale." Both, however, furnish 

 spermaceti, and in various osteological details come near together. 

 On the whole we incline towards separating the Cachalots from 

 the Ziphioids, and shall therefore commence with the former as 

 being in some respects the more primitive members of the family 

 Physeteridae. 



Sub-Fam. 1. Physeterinae. This sub-family may be thus 

 defined : Teeth in lower jaw numerous. Xo distinct lachrymal 

 bone. Stomach with only four compartments (? as to Kogia*). 



Of this sub-family the best-known genus is Physeter, including 

 the Sperm Whale or Cachalot. Of other reputed species we shall 

 speak later. The genus is characterised in the first place by its 

 large size as much as 82 feet of length have been assigned to 

 Physeter macrocephalus ; but Sir William Flower thought that 

 55 or possibly 60 feet might be a better approximation to the 

 greatest length of the Cachalot. The head is enormous, a third 

 of the length of the body, and terminates in a massive and 

 bluntish snout. This is, however, not so abruptly truncated as 

 is often represented in figures. According to Messrs. Pouchet 

 and Chaves, 1 it slopes forward two metres beyond the end of the 

 lower jaw ; the mouth is thus ventral and almost shark-like in 

 position, as is the case also with the Pygmy Sperm Whale, to be 

 considered later. In connexion with this peculiar position of 

 the mouth, it has been asserted Mr. F. T. Bullen figures it 2 - 

 that the Sperm Whale turns over upon its back to bite. The 

 blow-hole is single, and shaped like the sound-rhole of a violin ; 

 it lies upon one side, and is not median in position. The throat 

 is grooved as in the Ziphioids by two grooves. The dorsal fin is 

 represented by a whole series of lowish humps, decreasing in 

 elevation from before backwards. The pectoral fins are not large 

 relatively speaking. The great square head is not occupied 

 entirely by the skull ; the cavity lying above, which is of course 

 traversed by the tube ending in the blow-hole, is filled with the 

 spermaceti, which is fluid fat during the life of the animal. 

 Spermaceti also occurs in other Whales ; and that of Hyperoodon, 

 whence it has been extracted for commercial purposes, is said to 

 offer no differences of importance from the spermaceti of the 



1 Journ. de I'Anat. xxvi. 1890, p. 270. 

 2 The Cruise of the Cachalot, London, 1900. 



