1881. ] Geology and Paleentology. 337 
GHOLOGY AND PALZONTOLOGY. 
MAMMALIA OF THE Lower EOcENE Beps.—As stated in my re- 
port to Lieut. Wheeler in 1877, no vertebrate remains have been 
found in the Puerco beds, which underly the Wasatch in New Mex- 
ico, up to the present time. It was therefore uncertain whether 
they form the top of the Cretaceous or the bottom of the Tertiary 
series. I have recently obtained evidence of the existence of , 
Mammalia and turtles in them, so that their position is probably 
in the Tertiary division, as already suspected by Dr. Endlich and 
myself. Two species of flesh-eaters recently received from beds 
that may prove to belong to the Puerco group, do not belong 
to genera hitherto known from the Wasatch. The one which I 
first describe is of considerable interest as representing a very » 
primitive type of carnivorous dentition. : 
Periptychus carinidens, gen. et. sp. nov. Creodontium. Char. Gen. 
No distinct sectorial teeth, the first and second true inferior mo- 
lars similar. ey support a principal median cusp, a broad heel 
and a prominent anterior cingulum. The heel is more or less 
divided into tubercles; the anterior cingulum is on the inner side, 
and represents the anterior cusp of a sectorial tooth. On the 
inner side of the principal cusp a cingulum rises, forming a flat 
internal tubercle. Last molar not smaller than the others; pre- 
molars unknown. : 
This genus belongs to the Améblyctonide with Amblyctonus and 
Paleonyctis. Vt differs from both in the rudimental character of 
the anterior cusp, and from the former, in the presence of the in- 
ternal tubercle. In Mesonyx the heel has a median cutting edge. 
Char. Specif. Parts of both mandibular rami and the shaft of a 
humerus represent this species. They indicate an animal of the 
size of the red fox, but much more robust. The mandibular 
ramus is rather shallow and thick, and the molars are not large. 
The heel of the penultimate supports three tubercles, of which the 
external is the largest. The anterior cingulum supports a small 
cusp, and then rises to the internal tubercle, which is compressed. 
The sides of all the cusps are marked with distinct, well separa- 
ted, vertical ridges. Each extremity of the internal cusp is con- 
nected with the principal cusp by a ridge. The first true molar 
has fewer cusps. Those of the heel are scarcely distinct, and form 
a border which rises prominently into the flat internal tubercle, 
which forms a narrow longitudinal blade. The anterior cingulum 
has no cusp and does not rise into the inner tubercle. he prin- 
Length of crown first molar, .o115; width of do., .006; elevation © 
of do., .006, Length of second molar, .o11; width of do., .007; 
elevation of do ,.0065. Depth of ramusat do.,.020. The species 
isa 
sp. har. Gen. Fam. 
Leptictide, agreeing with /cfops and Mesodectes in possessing an 
