PETERSON : NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA 309 
PRINCIPAL SPECIFIC CHARACTERS. 
T3, Ct, Ps, M3. Occiput high. Region in front of the orbit elongated, with even 
slope of the skull, from the inion to the tip of the nasals ; frontal region flat between 
orbits, with deep grooves leading from supraorbital foramina to very nearly the end of the 
nasals. The posterior margin of the orbit lies immediately in front of a line drawn verti- 
cally from the anterior border of the glenoid cavity ; the infraorbital foramen is large, 
placed obliquely, and situated above the posterior part of P*. The posterior narial orifice 
has an extreme posterior position. P1 single-rooted and quite close to the canine, and 
there is a space separating it from P?. P? is in a continuous series with the teeth back 
of it. Py is absent. 
CRANIUM. 
The general contour of the cranium is quite similar to that of the peccary, Dico- 
tyles tajacu (Linneeus), especially the region anterior to the orbits. ‘The comparatively 
small size of the brain cavity, the high, sharp, and evenly sloped sagittal crest, 
together with the simple premolars, are characters which are striking, and at once 
separate this genus from the recent peccaries. The occiput is high and has a spoon- 
shaped excavation above the foramen magnum. ‘The lateral occipital crest is very 
prominent. From the junction with the sagittal crest it descends outward and 
downward for a short distance, then almost vertically downward nearly to the con- 
dyle, diminishing in prominence in the latter direction, so that the surface of the 
exoccipital is comparatively smooth 10 mm. above the base of the occipital condyle. 
The posterior temporal ridge forms a weak junction with the lambdoidal crest half- 
way between the occipital condyle and the inion. The strong -posterior temporal 
ridge points more strongly towards the conditions in the recent peccary and the hog 
than to those seen in the John Day species, according to Cope’s description of the 
latter. : 
The base of the skull is injured. The occipital condyle is present, but the con- 
tact is destroyed.’ The condyle is rather small and exhibits characters very similar 
to those in the peccary. There was probably a moderately large-sized foramen 
magnum, which separated the condyles proportionately less than in the peccary 
and the hog. The baso-cranial axis has a much greater angle than is seen in Dico- 
tyles tajacu. ‘This is due to the position of the posterior nares, which are relatively 
much farther back in Thinohyus siowxensis than in Dicotyles. 
The sutures in the cranium under discussion are entirely obliterated so that the 
outlines of the elements cannot be traced. ‘The basioccipital is broken posteriorly. 
7 The condyle is restored in its approximate position with plaster. 
