58 ARCHAEOTHERIUM. 
containing, on both sides the anterior two true molars, and the fangs of the last 
molar and of the last premolar. The other specimen, much the most important, 
consists of the greater portion of the skull of a young animal, in which the ante- 
rior two permanent true molars had protruded, but all the other permanent molars 
were yet concealed within the jaw. It is broken into two pieces, and is accompa- 
nied by fragments of both sides of the lower jaw. The upper part of the face, left 
orbit, and left zygoma are broken away, but upon the right side the latter two are 
almost perfect. The upper jaw, in its present condition, contains upon the left side 
the posterior five permanent molars (those concealed within the jaw having been 
artificially exposed), and upon the right side, the permanent true molars and the 
posterior two temporary molars. The fragments of the lower jaw consist of one 
of the left side containing the posterior five molars, of which the first and last had 
not yet protruded; and two of the right side, of which one is the angular portion, 
and the other contains the last temporary molar, the permanent last premolar and 
the first and last permanent true molars. 
Description of the Skull.—The form of the head of Archaeotheriwn Mortoni is so 
peculiar that I know of none among existing ungulata with which to compare it. 
Tn viewing it from above, it resembles more in general configuration that of the 
Lion or other species of Felis, than it does that of any of its own tribe now in 
existence. From the head of the Lion, however, it differs in numerous important 
points, among the most striking of which, are, the uniform height forward of the 
sagittal crest, the recession of the temporal fossx, the verticality of the zygomatic 
root, the existence of a post-orbital arch as strong as that of the Camel, the ver- 
ticality of the orbital entrance, the relatively great size and depressed character of 
the forehead, the extent of the lachrymal bone, the more prolonged and demi- 
cylindroidal form of the face, the advanced position of the infra-orbital foramen, ete. 
Lateral*View.—(P1. 1X., Fig. 1.) In the side view of the head, the upper outline 
descends slightly from the inion, then rises towards the forehead, and again descends 
along the face as in the Lion, but relatively not to the same extent. The outline 
of the inion appears more oblique than in the Peccary, and is intruded upon by 
the occipital condyles and a vertical convex prominence above them. 
The temporal fossa is quite transverse in its direction in comparison with that of 
the Hog and Peceary, and, as in these, its position is more posterior than in the 
Lion; but it is relatively longer and less deep than in the former animals, and is 
as much more capacious than these, as is that of the latter animal. Its increased 
capacity is not only produced by extension upward upon a strongly developed 
parietal crest, but also, as in the Choeropotumus and Lion, by the greater extension 
outwardly of the zygoma than in the Hog or Peccary. 
The root of the zygomatic process in association with the mastoid and paramastoid 
processes forms a remarkably strong scroll-like apophysis, which protrudes directly 
outward from the lateral margin of the inion, and expands like the mouth of a 
trumpet, is open below; and it leads to the meatus auditorius. Its anterior surface is 
an almost vertical convexity, nearly two inches in depth, and contributes very 
greatly to the extent of attachment of the powerful temporal muscle. Externally, 
the zygomatic process becomes abruptly narrowed to less than half the depth of its 
——— 
