PETERSON : NEW SULLINE REMAINS FROM THE MIOCENE OF NEBRASKA 311 
ary border. The postorbital process is more prominent than in the recent forms 
and is trihedral in section. It terminates inferiorly in a sharp point somewhat 
posterior to the postorbital process of the jugal. ‘The orbit is open posteriorly by a 
space of 12 mm. between the apices of the processes on the frontal and jugal. The 
posterior half of the frontals is flat and they are surrounded by the superciliary 
borders laterally, and by the prominent temporal ridges posteriorly. Anteriorly 
they gradually become convex to meet the maxillaries and nasals. The supra-or- 
bital foramina are close together and the deep furrows which lead from them ex- 
tend very nearly to the end of the muzzle. 
The jugal has a considerable depth below the orbit. ‘The postorbital process is 
strongly developed. The latter is heavy antero-superiorly and tapers gradually on 
the external and internal faces, forming a rather thin posterior edge. The process 
terminates in a subacute point. The orbit is oblique, irregularly oval, and of con- 
siderable size. On the anterior border the lachrymal tubercle divides the border 
into two emarginations. The one above the process is shallow, but the one below 
it is deeper, especially in the external face of the lachrymal. In this rounded 
emargination is also located the lachrymal foramen. The zygomatic arch is not so 
abruptly terminated at the lachrymal as in the hog, but continues in a gentle 
sweep forward to meet the superior border of the maxillary. The temporal fossa 
is proportionally much deeper than in the recent genera, while the orbital fossa is 
of about the same depth. The spheno-maxillary fossee in Thinohyus siowxensis are 
extremely deep, and divided by a thin septum of bone on the median line of the 
cranium placed antero-posteriorly and vertically. The posterior opening of the 
infraorbital foramen is large. The facial region of the skull shows no sutures. 
The alveolar border is low, and does not extend as far back as in the peccary 
and the hog. The deep fossa in front and below the lachrymal which appears 
in Dicotyles tajacu is much less pronounced in Thinohyus siowxensis. ‘The fossa 
in Thinohyus siowxensis is further forward. The infraorbital foramen is large, 
obliquely placed, and situated above the posterior part of p*. The alveolus of 
the canine presents, on the external face of the maxillary, an abrupt prominent 
swelling. Back of this eminence is a faint horizontal ridge, which is an indication 
of the much stronger ridge in the recent peccary. Immediately anterior to the 
canine alveolus is the deep groove for the reception of the inferior canine. 
The premaxillaries are heavy and greatly produced in front of the canine. The 
anterior palatine foramina are separated by a strong bony ridge; they are round 
and of considerable size. The posterior palatine foramina are close to the alveolar 
border and are opposite the anterior part of m.. The palate is long and narrow, 
