0. C. Marsh—New Tertiary Mammals. 205 
Measurements. 
Longitudinal extent of lower premolars and molars,..... 30°5 ™™- 
Extent of last three teeth, .. 050.00. 0ce cect ecco e eee es 16° 
Depth of jaw below last molar, ........-0++ seer ee eeees 75 
Length Of #ymphysigiis 60 i ee cen tee ee eae Ve 
Longitudinal diameter of canine at base,......----++++-- 3°75 
Space occupied by two left incisors, .....-++ ++++++++ 2° 
The specimen on which the.present description is based was 
found, in September last, by the writer, during the explorations 
of the Yale party in Grizzly Buttes, Wyoming. 
Viverravus (?) nitidus, sp. nov. 
_ A diminutive mammal, about the size of a weasel, is clearly 
indicated by a perfect penultimate lower molar, which agrees so 
nearly with the corresponding tooth of Viverravus graciles Marsh, 
that the species it represents may for the present be referred to 
that genus. Other remains in our collections probably pertain 
to the same species. The crown of this molar is composed of a 
posterior tubercle, which has its summit near the outer side; 
hext a pair of elevated, pointed cusps, of equal size, the exterior 
being slightly in advance of the other; and in front a small, 
slightly bifid tubercle. 
Measurements. 
antero-posterior diameter of penultimate lower molar,....- Fits 
ransverse diameter in front, ......-.eeee cere ere erneeeee 15 
_— diameter behind,......-.-+-. sees rere eeee es oo 
eight above jaw of central tubercles,.....+++-++++eer++> 3 
The above specimen was discovered last autumn, by G. G. 
Lobdell, J r., in the Tertiary shale near Henry’s Fork, Wyoming. 
Thinolestes anceps, gen. et sp. DOV. 
affinities, but their carnivorous characters appear unmistakable. 
apparently had the angle of the lower jaws inflected, and 
therium, and the two genera are evidently anes related. In 
the complete description, the characters and affinities of this 
peculiar roup, which may 
disenssed 
ort and stout. The 
The ] j in this species are sh 
ower jaws in this species oy caw or La 
teeth agree in number and general form w 
