GREGORY: NOrilARCTUS, AN AMERICAN EOCENE PRIMATE 



195 



Pinnipedia, perissodactyls and primates, and in the course of these observations the high diagnostic 

 value of the whole basicranial region has constantly been noted. Of course there are certain exceptions, 

 certain apparently sudden departures from type, as in the cases of Megaladapis, Palcropropithecus and 

 the Lorisiformes, which will be considered in detail in later sections of this work but, on the whole, the 

 basicranial region and especially the auditory region often affords a sure clue to relationship, even when 

 the dentition of divergent phyla is so diverse in character that it retains little evidence of their relatively 

 close kinship. 



Fig-. 72. KxtiTiiK s (if iiKihir ( nii^i i iici i(.n in the Vi\ erri(l;e. 



1. Bdeogalejacksoni. Ami'i . Mus. No. .36024. X i 



2. Cry plnproda fa-ox. Aiiier. Mus. No. .34861. X |. 



1. Bns^iuisrux iisliilus Ihini:^. Aiiu-r. Mils. No. X 



2. Adurns („iqa,s. Amcr. Mus. No. 326.50. X ii- 



Several striking instances of this kind are afforded by the families of the Carnivora Fissipedia, espe- 

 cially the Viverridse and the Mustelidte. A selection of skulls representing fifteen genera of recent and 

 extinct A^iverridse has been closely studied and it has proved possible to follow the divergent evolution 



