XII 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 cominence 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. No distinct lachrymal 
bone. Stomach with only four compartments (?7as to Kogic). 
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 leneth 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,’ 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 ?— 
that the Sperm Whale turns over upon its back to bite. The 
blow-hole is single, and shaped like the sound-hole 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 UV Anat. xxvi. 1890, p. 270. 
2 The Cruise of the Cachalot, London, 1900. 
