172 
ON SOME NEW AND LITTLE KNOWN OREODONT8. 
Genua MIACIS. 
'nrsil^teTo’rti.rMger basm of Wyoming, dittta from those hithe^o , 
known chiefly in its greater sise. It belongs with the other Bridge.- sucres to the 
division of tiigcnns in which the last lower molar has a single root although on one 
side of the jaw a very imperfect division of the alveolus is visible. The specif may 
be thus defined: Length of lower molar series, ra. .0.50, of premolar series, .027, of 
true molars, .023 ; depth of ramus below second molar, .020 ; no diastemata in lower 
dentition ; mental foramina below second and third premolars ; chin abruptly rounded. 
The specimen upon which this species is founded consists of the left mandibular 
ramus in which all the alveoli are preserved, part of the right ramus retaining the 
first and second molars, a dorsal vertebra, portions of ulna, radius, tibia, fibula, and 
several metajiodials and phalanges. 
The inferior dentition of the genus is well known, and the only features of 
interest in this specimen are the absence of diastemata and the incisor formula, 
which can now be given. The closed dental series is repeated in the Uintacyon 
( edax of Leidy, but the type specimen of this species shows eight teeth in 
the molar series. Professor Cope regards the additional tooth as abnormal, but 
this may not lie a correct view. An analogous case is found in among recent 
dogs. The symphysis in Miacis hathygnathus is narrow and the incisors closely 
crowded togidher ; as Dr. Schlosser ^ has conjectured, they are three in number and 
are small and have very compressed fangs. As in several other genera, the first and 
third of the series ari.se at the same level while the median one is forced out and 
upwards. In view of the very small space occupied by these teeth, it may well prove 
to Ik* the ca.se that other creodonts which have been supposed to have a reduced 
numlM'r of incisors, in reality po.ssess the full number. 
'I'he masseteric fossa is deep, with very prominent anterior edge ; the condyle is 
heavy and iK'neath it on the inner side the ramus is ver\' concave, almost like an incip 
ient intlection ; the angle ends in a short slender hook ; the horizontal ramus is stout, 
tkx'p and nithcr short, and the chin abruptly rounded ; the canine is directed upwards 
and not obliquely forwards as in Uintacyon edax. 
'I'he doi-sal vertebra, which is from the anterior part of the region, has a small, 
slightly opisthoccrlous centrum ; the transverse processes are short and stout ; the prezy- 
gaiKiphyscs unusually large and quite strongly convex in the anterio-posterior direc- 
tion, the jiostzygapophyses of corresponding size and concave in the same direction, the 
sjiine is trihedral, long, stout and directed strongly backwards. This vertebra resem- 
bles quite closely the third dorsal in the dog, but with proportionately stouter spine. 
The fragment of idna, comprising a portion of the shaft and the lower half of the 
sigmoid notch exactly resembles the corresponding part in Didyrnictis. The lower part 
* Morph. Jahrb. Bd. xii., p. 293. 
