204 O. C. Marsh—New Tertiary Mammals. 
Measurements. 
Space occupied by lower premolars and molars, .........- 47598 
Space occupied by last three molars, .........6--eeeeeee 26° 
Antero-posterior diameter of penultimate lower molar,..... 9 
SPADA VOTES SAIIOROT eg «pene Fake ea os «4s el ches’ 
Depth of jaw below this molar, ............... 4 i hain 125 
The specimens on which this description is based were found, 
in August last, by Mr. O. Harger, at the same locality as the 
preceding species. 
Limnocyon agilis, sp. nov. 
A still smaller species, apparently of the same genus, is well 
represented by the greater portion of a skull with teeth, and 
the more important parts of the skeleton of the same individ- 
ual. In the lower jaws, the premolars are separated from 
each other and from the canine, and the first premolar has but 
a single fang. The first upper premolar is separated nearly its 
own longitudinal diameter from the canine. The penultimate 
upper molar has its elevated pair of cusps more closely united 
than in the last species. The present animal had a long tail, 
and claws resembling those of a fox. 
Measurements. 
Space occupied by three lower premolars, .........+-+++ 27°6" 
epth of jaw below third lower premolar,..........-+.+ 
The above remains were found by the writer, in September 
last, in the Tertiary shale of Grizzly Buttes, Wyoming. 
Thinocyon velox, gen. et sp. NOV. 
A small carnivore, about as large as a cat, is represented hy 
somewhat resembles in its proportions that of Zymnocyon, but 
it is more elongated, and the symphysis is more nearly horizon- 
tal. The angle of the lower jaw is inflected, thus ge in- 
dicating the marsupial affinities of the species. The condyle, 
also, was evidently but little elevated. e number of teeth in 
each lower jaw was nine, divided as follows: Incisors 2, canine 
1, premolars and molars 6. The incisors are small and com- 
ressed. The canine is large, and nearly round at the base. 
e last two molars are tubercular; and the four anterior teeth 
compressed, and each has two fangs. 
