284 THE OSTEOLOGY OF ELOTHERIUM. 
Kowaleysky inferred from the study of his specimen that the foramen ovale “ nicht 
als selbstiindiges Foramen existirte, wie z. B. bei den Ruminanten, sondern mit dem For. 
lac. med. verschmolzen war, wie bei den heutigen Suiden und bei Hippopotamus” (’76, 
p- 483). This is probably a mistake; at all events, it is not true of the American 
species, in which the foramen ovale is a long, conspicuous opening, of oval shape, perfo- 
rating the alisphenoid. As in the ungulates generally, there is no separate foramen rotun- 
dum, that opening being fused with the foramen lacerum anterius. The latter is a large 
and somewhat irregular opening, which notches the anterior border of the alisphenoid, 
passing between that bone and the orbitosphenoid. The optic foramen is small and well 
separated from the foramen lacerum anterius, lying in front of and at a slightly higher 
level than the sphenoidal fissure ; it does not open so far forward as in L. magnum, and, 
in consequence, it does not form such a remarkably elongated canal as in the European 
species (see Kowalevsky, 76, Taf. XVI, Figs. 1 and 3, dd), but, on the other hand, it is 
far from being a simple perforation of the orbitosphenoid, such as occurs in the recent 
ungulates. This elongation of the optic canal should probably be correlated with the 
very small size of the brain, which would seem to have been relatively smaller than in 
the ancestors of the genus. Though the orbits are far behind their primitive position, 
the backward shifting of the optic tract would seem to have kept pace with the change in 
the position of the orbits. 
The posterior palatine foramina are large and conspicuous openings, placed at the 
maxillo-palatine suture, and separating the two bones at these points; the palatine plates 
of the maxillaries are deeply grooved for some distance in front of the foramina. The 
incisive foramina are likewise large, invading both the maxillaries and the premaxilla- 
ries; indeed, their size preyents the development of any considerable palatine processes 
on the latter bones. These foramina are in very marked contrast to those of ippopota- 
mus, in which the enormously expanded and massive premaxillaries are perforated by 
two small and widely separated openings; in Sus also the incisive foramina are propor- 
tionately much smaller than in Hlotheriwm. The infraorbital foramen is large and is 
separated from the orbit by a considerable interval, opening above the anterior border of 
p 2. In front of the foramen a deep groove channels the outer face of the maxillary for 
a short distance. The canal itself is much elongated, in correspondence with the great 
length of the jaws, and its posterior orifice, within the orbit, is very large. The lachry- 
mal foramen, which is single, is quite small and is placed inside of the orbit. 
The supraorbital foramen is subject to some variation in the different species. In 
E. ingens, from the Titanotherium beds, these openings are of good size, are placed quite 
near to the median line, and have well-marked vascular channels running forward from 
them. In specimens of #, mortoni from the Oreodon beds, and in the very large species 
