552 



ZOOLOGY 



SECT. 



compressed, conical, pointed form. The prevailing dental formula 

 of the Seals is 



.314 1 



i. y c. =-, p. j, m. Y = 34. 



In the Walrus the adult formula is 



.11 



. = 18. 



The upper canines take the form of large, nearly straight tusks. 



In the large order of the Rodents the dentition is remarkably 

 uniform, and, in all its general characters, resembles what has 

 already been described in the Rabbit. But the second, smaller 



FIG. 1209. Left lower carnassial teeth of Caraivora. I, Telia ; II, Canis ; ///, Herpestes ; 

 IV, XiUtra ; V, Meles ; VI, ITrsus. 1, anterior lobe (paraconid) of blade ; 2, posterior 

 lobe (protoconid) of blade ; 3 , inner cusp (metaconid) ; 4, talon (hypoconid). (After 

 Flower and Lydekker.) 



pair of incisors of the upper jaw is present only in the Hares and 

 Rabbits ; the number of pre-molars and molars varies from 



p. ?.?toj.|,m.f, 



and they may develop roots. 



In the Insectivora the dentition is heterodont, complete, and 

 diphyodont. All the teeth are rooted. There are never fewer than 

 two incisors on either side of the lower jaw. The canines are not 

 of large size. The crowns of the molars are beset with pointed 

 tubercles. 



In the Chiroptera the dentition is complete, and the teeth are 



