PHYSETERID-3E. 



53 



Suborder ODONTOCETL 



Teeth are always present after birth ; the functional ones are 

 generally numerous, but sometimes are reduced to a single pair, and 

 are occasionally wantiDg ; baleen is absent. The cranium is more 

 or less asymmetrical, and the nasals are reduced to nodules which 

 do not roof over the narial passagest The tympanic is not anchy- 

 losed to the periotic, and is of. a more open structure than in the 

 !Mystacoceti. 



Family PHYSETERIDJE. 



No functional teeth in the upper jaw ; mandibular teeth various, 

 and often reduced in number. The bones of the cranium are raised 

 so as to form an elevated crest or prominence behind the nares. 

 The anterior f acette of the periotic for articulation with the tym- 

 panic is quite smooth ; and the posterior tympanic surface of the 

 former is broad, and carries a median longitudinal ridge. 



Subfamily Physeterin^. 



The mandibular teeth are numerous and implanted in a long 

 groove partly divided by imperfect septa. 



Genus PHYSETER, Linn.^ 



There are from twenty to twenty-five mandibular teeth, which 

 have no enamel ; the mandible is very long and narrow, the sym- 

 physis occupying more than half its length. The atlas is free, but 

 all the other cervical vertebrae are fused into a solid mass. 



iBl^p^eter macro cep!jalxi5, Linn.^ 

 Hab. All tropical and temperate seas. 



39264. The ventral half of the atlas vertebra ; from the Pleisto- 

 cene (?) of Uruguay, South America. As this specimen is 

 indistinguishable from the corresponding bone of the ex- 

 isting Cachalot, it may be at least provisionally referred 

 to the same species. 



Presented by Captain J. Farish, B.N., I860. 



1 Syst. ^'at. ed. 12, vol. i. p. 107 (17l)()). - loc. cif, ' 



