16 Bulletin American Museum of Natural History. [Vol. XXXIV, 
Anacodon cultridens sp. nov. 
Type, No. 15638, upper and lower jaws from Lysite beds of the Big Horn Valley, 
at the head of Fifteen-mile Creek. 
Distinctive characters: my-2=50; p* subtrigonal with cusps higher than in 
) A. ursidens, no trittocone or 
tetartocone; molar cusps less 
flattened or obscured by cren- 
ulations. 
This species is about 
one-fourth larger in lineal 
measurements, but more 
primitive in the construc- 
tion of molar and premolar 
teeth. The jaw is flanged 
anteriorly, but the flange 
does not appear to be so 
deep as in A. ursidens. 
The specimen consists of 
upper and lower jaws ap- 
Fig.11. Anacodon cultridens, upper and lower cheek tlv ck f 
teeth, crown views, natural size. Type specimen, Lysite parently wl some irag- 
beds, Big Horn Basin, Wyoming. ments of the skull, but the 
bone is badly preserved 
and obscured by hard matrix, so that little can be determined with cer- 
tainty beyond the characters of the premolars and molars, p?-m?, p4—m; 
which are in good preservation. 
MIACIDA. 
This family is represented by six genera and fourteen species in the Lower 
Eocene formations. Four of the genera survive into the Middle Eocene. 
The Miacide are a group of genera divergently specializing into predaceous 
and frugivorous adaptations, ancestral to the Fissipede carnivora, and to 
some extent foreshadowing their broader groups. In the Lower Bridger 
they are divided primarily into two groups, the Viverravine with one genus 
Viverravus, and the Miacinee with Uintacyon, Miacis, Oddectes and Vul pavus. 
Following these divisions down into the Wasatch horizons, we find the 
Viverravine (represented by Viverravus and Didymictis) still well distin- 
guished from the Miacine (represented by Uintacyon, Miacis, Vassacyon 
and Vulpavus), but the genera of each group approximate, especially 
