ANCHITHERIUM. gf) 



in this the process of the os frontis, which, in the Horse, contributes to its forma- 

 tion, is brolien away to its base, leaving a triangular surface, two sides of which 

 measure only three lines, the other four lines. 



The lachrymal bone externally is almost as concave as in the Sheep, leading us 

 to suspect the existence of shallow larmiers. Its orbital margin is acute, and 

 within this, at its lower part, there is a single, vertically crval, lachrymal foramen. 



Superior View. — (XI. 2.) The upper view of the cranium of AncUtlierium also 

 resembles very much that of the Horse. The forehead is a little more flat, and 

 extends into a relatively larger triangle posterior to the coronal suture, which holds 

 a corresponding position. The anterior margin of the frontals are not extended 

 into long angular processes between the bases of the ossa nasi, as in the Horse, 

 but form together a very obtuse angle. 



The sides of the face, as formed by the lachrymal bones and the upper maxillaries 

 below them, descend much more abruptly from the anterior orbital processes of the 

 ossa frontis, or they approach the vertical line much more nearly than in the Horse. 



In the specimen, the sagittal suture of the frontals and parietals is. still open. 



Posterior Vieio. — (X. 20.) The inion, from its summit being relatively less broad, is 

 more triangular in outline than in the Horse. Its middle part bulges over the foramen 

 magnum, anS above this point is depressed upon each side of a slight vertical ridge. 



The relative position and form of the condyles and the form of the foramen mag- 

 num are very much the same as in the Horse, except that the inferior surfaces of 

 the former are more nearly horizontal, and diverge more posteriorly and approach 

 nearer anteriorly. 



Above each condyle, as in the Horse, there exists a crescentic depression of the 

 occipital surface. 



Inferior Vieio. — (X. 21.) The basilar prqcess is relatively broader, less deep, and 

 more angular than in the Horse, and upon each side it presents a long impression, 

 and at the middle is elevated into a superficial tuberosity for muscular attachment. 



The junction of the basilar process with the sphenoidal body occupies the same 

 position as in the Horse, being on a. line with the anterior margin of the foramina 

 lacera, but in the specimen it is obliterated. 



The sphenoidal bodies are slightly convex compared with those of the Horse, and 

 the posterior does not present the deep muscular impressions existing in that animal. 



The paramastoids hold the same relative position to the condyles as in the Horse, 

 and as in this between them a deep fossa exists, at the inner side of which the 

 anterior condyloid foramen is situated. 



The OS tympanica is relatively slightly more dilated than in the Horse; and the 

 OS petrosa abuts closely against the basilar process. 



The base of the styloid process, alone remaining in the specimen, is embraced 

 anterorinternally by the os tympanica. 



The foramen lacerum is large anteriorly, but becomes a very fine crevice poste- 

 riorly. 



The inner portion of the glenoid articulation, which alone is preserved in the 

 specimen, resembles very much that corresponding to it in the Horse. The post- 

 glenoid tubercle is relatively much more robust; and is mammillary in its form. 

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