1881.] Geology and Palecntology. IOI9 
navajovius Cope must be separated as a distinct genus, since the 
apices of the crowns of the last two molars have two cusps. This 
genus may he called Drssacus. (4) It results that there are four 
species of Mesonyx: M. ossifragus Cope, M. lanius Cope, M. 
obtusidens Cope, and WZ. gaudryi Fisch. MV. ossifragus was the 
largest Creodont of the Eocene, equaling the largest grizzly 
bear in the size of its skull. 
The number of possible combinations of tubercular and tuber- 
cular-sectorial molar teeth is considerable, and many of them 
are represented in the genera of the Creodonta. A new one 
must now be added, in a genus which has, in the lower jaw, two 
tubercular sectorials, and one tubercular: posterior to them. The 
genus thus stands between Stypolophus and Didymictis, but is 
nearer the former than the latter, since it has three true molars. It 
differs further from both in having but three premolars and a wide 
diastema. The canine is well developed. I call the genus Lifo- 
dectes, and describe two species, both from the Lowest Eocene, 
probably Puerco, of New Mexico. 
Lipodectes penetrans, sp. nov., represented by a left mandib- 
ular ramus with three of the molars preserved. The last has 
along heel; the first and second true molars are alike, an 
cusp. The posterior border rises into an acute cusp, which 
is internal to the middle line. The internal border of the 
heel is not elevated, and the surface is the oblique inner face of 
the external cusp. The anterior cusps are only moderately ele- 
vated and the cusps are acute. The enamel is smooth, and there 
is a low cingulum on the external base. The first (second) pre- 
molar is two-rooted, and has a large base. The second (third) 
consists principally of an elevated cusp with a subtriangular sec- 
tion. The heel is very small and acute, and there is no anterior 
basal tubercle. The internal face is strongly grooved in front. 
Canines directed upwards, with robust base. Symphysis short. — 
Length of molar series, .043; of premolars, .o19; of diastema, 
012; length of base of last molar, .o10; do of canine, .007; 
depth of ramus at last molar, .018; of diastema, .o15. As large 
as, but more robust, than the red fox. 
Lipodectes pelvidens. This species is about the size of L. pene- 
trans, and differs from it in the less carnassial character of the 
inferior molars. The anterior cusps are relatively smaller in 
every way, and are more distinctly separated by deeper emargina- 
tions. The heel is wider, and has a less elongated external mar- 
ginal cusp. The inner margin of the heel is elevated, enclosing 
a basin-like fossa, and rises into a flat cusp posteriorly. There is 
_ 1 Paleontological Bulletin, No. 33, p. 454. ss 
