PETERSON > DESCRIPTION OF NEW RODENTS 179 
Euhapsis platyceps gen. & spec. nov. 
Type, Plate XVII., Figs. 5, 6, 7, 8. 
GENERIC CHARACTERS. 
P-m;3. Teeth hypsodont. Premolar x has the transverse diameter very nearly as great 
as the antero-posterior. The teeth in their worn condition have no external enamel inflec- 
tions. The length of molars 7 and x together is very little greater than that of the preced- 
ing tooth (pz). The zygomatic arches are much expanded. The length and breadth of 
the skull is about equal. The occipital surface slopes forward. Parietals broad and 
short. No postorbital processes on the frontals. The tympanic bulla is inflated and flask- 
like. Bastoccipitals not excavated, but slightly keeled. Mastoid processes directed outward, 
instead of downward. 
SPECIFIC CHARACTERS. 
Incisors strong, somewhat trihedral in cross-section, anterior face very little rounded, 
and with a heavy band of enamel. Muzzle heavy and short. Infraorbital foramen 
small. Orbit wrreqular and high. Interorbital region moderately constricted. The space 
between incisor and p* on premaxillary very little arched.  Basi-eranial region back of 
cheek-teeth short. Otic bulla with long and greatly constricted tube.  Occiput low and 
broad. Two small foramina on either side of the median line of the basioccipital. Skull 
broad and depressed. Animal somewhat smaller than Aplodontia or Cynomys. 
The type (No. 1220) of this new genus and species consists of the skull and por- 
tions of both mandibular rami, and was found in the Upper Monroe Creek beds, 
near the head of Warbonnet Creek, Sioux Co., Nebraska. This horizon immediately 
underlies the Harrison (Demonelix) beds. The specimen was found close to a nearly 
complete skeleton of ? Mesoreodon, and in the same sandstone ledge, where the four 
skeletons of Promerycochwrus were found, three of which are now on exhibition in 
the Carnegie Museum. In the same horizon were also found remains of small car- 
nivores of the family Canidx, small species of camels, and turtles, which are not yet 
identified. 
The general outline of the skull presents similarities to that of Mylagaulus 
monodon (Mem. Americ. Mus., 1901, pp. 877-879), and Ceratogaulus rhinocerus (Bull. 
Americ. Mus., Vol. XVI, 1902, pp. 291-300). The extreme width of the cranium 
in comparison with its length, the wide and forward sloping occipital surface, and 
the general depressed appearance of the skull, are especially suggestive of the Myla- 
gaulide. A detailed comparison, however, shows that the animal was perhaps more 
nearly related to Stencofiber. 
