361 



almost the only difference was in the size and in the strength of the 

 marking on the skull, and in the size of the canine teeth. The full 

 number of the teeth of these animals is developed early in life ; and 

 the canines of the second set are gradually developed, the roots being 

 far in the socket, and protruded as the jaw enlarges. 



The changes in the form of the palate and of the distance between 

 the teeth of the same set in the younger and older skull of the same 

 species after they have obtained their full set of teeth is very great, 

 quite as much as the difference in the external form of the skull pro- 

 duced by the development of the occipital ridges, &c. 



The following are the measurements of the different skulls in 

 inches and eighths : — 



i-j CD 



CB 3 



! ? 



o ^ 



>*s _ 



* I 



CD 2 



era 



Cn tn 

 © OS 



en os 



#- CO 



© 



Callorhinus ur sinus, 

 adult. 



co cp 

 to © 



CO — 

 © © 



OS © 



Arctocephalus monte- 

 riensis, adult. 



#>. © 

 *■> © 



tK © 

 © © 



Arctocephalus hookeri, 

 half-grown. 



© © 

 © ^ 



© CO 



to © 



© t— 

 © © 



Arctocephalus lobatus, 

 very old. 



to © 



*»> © 

 © © 



i4- CO 

 © © 



Arctocephalus nigres- 

 cens. 



Cn en 



© 



© CO 

 to © 



to © 



Arctocephalus gillespii. 



© © 

 © © 



Cn O 

 tO 



Arctocephalus dela- 

 landii. 



to to 

 co co 

 © © 



05 V\ 



© 



05 «<l 

 I— 1 to 



Arctocephalus, young 

 from California. 



co © 



© 05 



© to 



Otaria leonina, aged. 



© © 



C" 



to ^ 



© 



Otaria leonina, balf- 

 grown. 



