1884. ] The Creodonta. i 261 
II. Inferior molars tritubercular without heel, 
No sectorial teeth; tibia and fibula codssified.............. . s o o o Chrysochloridide. 
IH. Inferior molars tritubercular-sectorial or quadritubercular, 
a, No superior sectorial teeth. 
ene DA TR a e o iaeaea h erena ea te Na Cea oO Centetide. 
Tibia fibula codssified; external tubereles of saperi molars wih! 
CbniG WO CieviCles ool ul sc eks coe .Mythomyide} 
Tibia ad fibula codssified ; external tubercles two Vs; clavicles..... --- Lalpide. 
aa, First true superior molar sector 
Tibia and fibula distinct; no tubercular molars......... Oxyenide. 
aaa, Fourth superior premolar sectorial. 
Tibia and fibula distinct; true molars tubercular,...........0.s0000000sMiacida. 
The number of genera and species embraced by these families 
is as follows. The extinct forms only are enumerated, and 
those of North America are specified : 
Families. Genera. Species. N. America, 
Mesonychide saae... es nas A ORS A 
Hyænodontidæ è I I0 3 
ryotordidæe REPT ERTL CEE ee Pag aed * 
e Sb in ss kn oa hae OE sasak 18 44 37 
Mythomyide ......... * * 
Talpide .... * * 
E a aaan 3 7 4 
Miacidæ..... 2 12 12 
ROM E cs nas anne he Oak 28 80 63 
The affinities of these families may be expressed in the follow- 
nt diagram, which may be regarded as an attempted phylogeny 
Insectivora Carnivora 
Talpide © Mythomyide Miacide  Oxyænidæ _ 
LEUT rR iae 
Chrysochlorididæ Centetidse Hyznodontida 
ae 
=o Hes Mesonychidz 
Mesozoic * forms. 
1 
This family is sometimes called the Po‘amogalide. Mythomys is, however, the 
“ame first published, with a description, for the typical and only genus. 
