12 



WHALES AND DOLPHINS. 



swimmers, which migrate in numerous shoals 

 when driven on by the ice-masses, by which 

 they often get forced into bays and there 

 hemmed in and suffocated. The Europeans 

 do not often pursue them, but the Eskimo 

 are very eager in the chase of this animal, 

 prizing its flesh very highly. 



The Sperm-whale Family {Physeterida). 



This family consists of those forms which have fully developed 

 teeth only in the lower jaw. 



As representative of a group of pretty 

 numerous but little -known cetaceans with 

 only two permanent teeth in the lower jaw, 



Fig. 140. — The Bottlehead or Common 1 « 



we have selected the Bottlehead or Common 

 Beaked Whale [Hyperoodon rostratus), fig. 

 140. This whale, which attains the length 

 of about 26 feet, usually inhabits the Arctic 

 Seas round Greenland, but some individuals 

 have been stranded on our coasts. The first 

 good description of this species was given by 

 John Hunter, to whom it owes its English 

 name, and whose description was based on 

 a specimen caught in the Thames. In winter 

 this whale migrates pretty regularly as far 

 as the waters of Iceland and the Faroe 

 Islands. 



The back part of the head is swollen, and 

 this swelling is still further increased by a 

 remarkable accumulation of fat in front of the 

 nostrils between two vertical plates which 



a wi 



rostratus). 



stand up like walls on the outer edges of the 

 jaw-bones (maxillae). The flattened snout is 

 continued in front of this swelling. The Ice- 

 landers compare its head to that of a duck. 

 The opening of the mouth is small. In adult 

 animals there are only two large conical teeth 

 in each half of the lower jaw near the front. 

 But in young animals, in each half of the jaw 

 both above and below, a dozen small teeth 

 begin to be formed, but they never cut the 

 gum and are soon re-absorbed. The flij^pers 

 are very small, the dorsal fin pointed and 

 also small, the tail fin not divided into lobes. 

 The colour is gray, inclining to black, darker 

 on the back than on the under side. The 

 animals feed on cephalopods. In the northern 

 waters they are very eagerly hunted for their 



