NOTES ON THE CANIDE® OF THE WHITE RIVER OLIGOCENE. 363 
Mracis vrinrensis Osborn. 
Bull. Am. Mus. Nat. Hist. N. Y., Vol. vu, p. 77. 
Size rather less than that of D. hartshornianus; upper sectorial relatively small and 
tubercular molars large ; premolars short and thick. 
Measurements. 
MM. 
Men cths pe scOMMeniMClusivetc-sseccons cecccsetanascneeressuccacssceessescecasccsssceescscccostcvecuitecservoseans 37 
P * length 
P+ length 
P= widthes:-<---ce Sa0dD 5 ROESDOE COSC ANS ISHSOS OS DUCEE SAEED” -o/aucH UNE BoC Gac0 Bocas Bode Su SuSoCeaae eee aceaee aaEeReEeere 11 
M + length... 
Me Dev dthv eens faeces ae cea behest RELL. Se oatbee ee gd i tad Feil ceded lal ty 
aU EAS ay Tea fl Nogebeaecoaaho I eaco- bo eas ageo NSO RO Repo TeSUer ao Jon ec ERE EE ne Ere SRS EERE 
INCE TIGh it soccccs bo aencacbSdanc sad See qeande Yondos ed aacosaconcc EISEN GELS a cicee ecSCeHCuG Ie ne SUR OEE ene eee Hed) 
. 
Fie. A.—First upper molar of the left side : 
1, of ? Miacis wintensis. 2, of Daphxnus hartshornianus. 3, of Canis latrans. x, cusp usually regarded as the 
protocone. 
If Ihacis be rightly regarded as having a place in the canine phylum, then the 
structure of its upper tubercular molars is of great interest and will require a revis- 
ion of the current views concerning the homologies of the cusps in the upper molars of 
the dogs. In Cunis, according to the usual interpretation, m 1 is composed of two external 
cusps, the para- and metacones, and at the apex of the triangle of which the para- and 
metacones form the base, an unpaired internal cusp, the protocone, with the proto- and 
metaconules on the anterior and posterior sides of the triangle respectively. Internal 
and somewhat posterior to the protocone is a large crescentic cusp, which is commonly 
regarded as an enlargement of the cingulum, although in unworn teeth a faint cingulum 
may be traced all around this crescentic cusp and is continuous with the prominent cin- 
eulum which bounds the anterior wall of the crown. If this interpretation of the cusps 
be correct, and further, if Jfacis is ancestral to the Canide, them min the Uinta 
genus is without a protocone and has only the para- and metacones, minute conules and 
the large inner crescentic cusp. Itseems much more rational to conclude that the lat- 
ter is really the protocone and that the cusp which has been so named in Canis is an 
additional element subsequently developed. In Daphenus this inner crescentic cusp and 
