36 BRITISH MAMMALS 



the coasts of Devonshire, North Wales, Lincolnshire, Scotland, 

 and Ireland. 



FAMILY: PHYSETERID^E. SPERM AND ZIPHIOID WHALES 



This family is supposed to differ at the present day from almost 

 all the dolphins in that there is an absence of functional teeth in 

 the upper jaw. This is perhaps rather a foolish distinction, since, 

 apart from the similar case occurring in Risso's grampus, we now 

 know that in one genus at least (Kogia) of sperm whales there are 

 two functional teeth on each side of the upper jaw, and in most of 

 the Physeteroids there are rudimentary teeth in the upper jaw 

 which do not cut the gum. Moreover, remains of fossil sperm 

 whales in Europe and South America show that in these earlier 

 types there were teeth in both jaws. But the Physeteroids also 

 differ from dolphins and from other whales in the remarkable 

 construction of the back portion of the skull, which rises into a 

 high ridge or crest behind the nasal aperture. This family is, 

 or was, represented in British waters by the sperm whale and the 

 beaked whales. 



SUB-FAMILY: PHYSETERIN^E. SPERM WHALES 

 Physeter macrocephalus. THE SPERM WHALE, OR CACHALOT 



This has perhaps in its time been the most gigantic cetoid 

 development in size, for there are credible stories, supported to 

 some extent by the evidence of teeth, that sperm whales, 80 ft. 

 long existed in the Pacific off the coast of South America. 

 But at the present day the largest known males have not been 

 found to attain a greater length than 60 ft. The female sperm 

 whale is proportionately much smaller than the male, being 

 scarcely over 30 ft. long. The True Sperm Whale has an 

 enormous head, in length about a third of the total length of the 

 body. There is a marked prominence at the back of the head, 

 which corresponds (though there is a great mass of blubber behind) 

 to the great upward development of the crest of the skull in the 

 Ziphioids. The blow-hole, or outer valve of the united nostrils, 



