SEALS AND WHALES OF THE BRLTLSH SEAS. 85 



ODONTOCETI (TOOTHED WHALES), 



PHYSETERIDyE. 



The second sub-order into which tlie Cetacea are divided, is the 

 Odontoceti, or Toothed Whales. In this section, baleen is never present, but 

 well-developed teeth are found in one or both jaws of the adult ; in some 

 species they are very numerous ; sometimes, though rarely, deciduous. The 

 blow-hole is single, and the skull generally asymmetrical, or not precisely 

 alike on both sides of the medial line. Professor Flower divides the 

 Odontoceti into three families, one of which, the Platanistidoe, as already said, 

 is found only in India and South America : the other two, Pkyseteridce 

 and DelphiiiidcB, are represented in our Fauna by about fifteen species. 



Of the PJiyseteridce, four genera are represented in the British fauna 

 by four or five species ; namely, one Physeter, the Sperm Whale ; two 

 Hyperoodons, the common Beaked Whale, and a doubtful species called the 

 Broad-fronted Beaked Whale ; one Ziphitis, Cuvier's Whale ; and one 

 Mesoplodoii^ Sowerby's Whale. 



SPERM WHALE, OR CACHELOT. 



By far the most conspicuous species of this interesting group is the Sperm 

 Whale, Physeter macroccpJiahis (Linnaeus), which rivals the Right- Whale in 

 commercial importance, and in the value of its products. This species has a 



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