SPEEM-WHALES, ETC. 61 



feet, the lower teeth vary in number from fifty to sixty on 

 each side, and are characterized by their large size and 

 pointed crowns, upon which there is not a trace of enamel. 

 Another characteristic feature of this animal is the 

 enormous size of the head, which terminates in an abruptly 

 truncated muzzle of great depth, and in a cavity of which 

 is contained a peculiar oily substance, yielding when 

 refined the well-known spermaceti. An even more valuable 

 product of this animal is ambergris, which, while accumu- 

 lated as a concretion in the intestine, is generally found 

 floating on the surface of the sea ; in appearance it is an 

 amber-coloured substance, containing a number of the 

 horny beaks of the squids on which the sperm-whale 

 subsists. 



Omitting mention of the lesser sperm-whale — the only 

 other member of the first division of the family — we pass 

 on to mention the bottle-nosed and beaked whales, 

 characterized by having all the lower teeth, with the 

 exception of a single pair, rudimentary, and concealed in 

 the gum. In the bottle-noses — so named from the extreme 

 convexity of the crown of the head of the adult males, 

 which rises suddenly above the short beak — there is but a 

 single pair of teeth, situated in the front of the lower jaw, 

 and even these are invisible during life. These whales, 

 of which there is but a single well-defined species 

 (Hyperoodon rostratus), although not exceeding some thirty 

 feet in length, are valuable on account of their oil, 

 as well as from yielding spermaceti from their skulls. In 

 contradistinction to the sperm-whale, they carry, in 

 common with the beaked whales, a large back-fin. 

 In the beaked whales, of which there are three existing 

 genera, the skull is produced into a long beak, of which 

 the upper half is formed by a solid bone of ivory-like 

 density ; while in the lower jaw there are either one or two 

 pairs of teeth, which, although variable in position, are 

 generally of large size. It is one of these whales (Mesoplodon 

 layardi) which is alluded to in the chapter on ' ' Tusks and 

 their Uses," as being provided with teeth of such a size 

 as actually to impede the free opening of the mouth. 

 From their general avoidance of the neighbourhood of 



