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 pemnanent 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 Shnll. — The form of the head of Arcliaeotherium Mortoni is so 

 peculiar that I know of none among existing ungulata with which to compare it. 

 In 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 fossa), 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 adv.anced position of the infra-orbital foramen, etc. 



Lateral View. — (PL IX., 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 Peccary, 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 Choeropotamus 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 



