Sub-Order ODONTOCETI— TOOTHED WHALES 



Family PHYSETERIDiE. 

 Genus Physeter. 



THE SPERM WHALE OR CACHALOT. 



Physeter macrocephalus, Linnaeus. 

 Plate 45. 



The various members of this group {Odontoceti) are distinguished by 

 the possession of teeth, which may be numerous in both upper and 

 lower jaws, or confined to a single pair in the latter ; there is also no 

 whalebone. The nostrils are united below the surface and form one 

 external blowhole. The skull is not symmetrical. 



The Sperm, by far the largest of these toothed whales, measures up 

 to and over 60 feet, the females being considerably less. The huge head, 

 appearing as if cut off abruptly in front, and taking up about one third 

 of the whole length of the body, is curiously shaped, the massive upper 

 part being adapted as a sort of well or receptacle to contain the valuable 

 oily fluid known as spermaceti. The blowhole is placed very far for- 

 ward on the left-hand side and near the extremity of the head. The 

 first vertebra of the neck is free, the others united. 



The upper jaw reaches considerably beyond the lower. 



One or more rounded protuberances on the back represent the dorsal fin. 



The flippers are broad and unpointed. In the lower jaw are from 

 twenty to twenty-five pairs of hooked teeth, those in the upper jaw 

 being rudimentary and buried in the gum. 



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