24 



E. M. MUSEUM MEMOIRS. 



Leidianunt skull is in fine preservation, but even here some of the most impor- 

 tant points are concealed by age and fracture. Many of the sutures of the 

 bones can, however, be clearly traced. 



Partial Description of Skull. The Squamosals form a long suture with the 

 parietals, and the latter have only a short connection with the alisphenoids. The 

 alisphenoids in turn unite for some distance with the frontals, and form also a 

 short connection with the unusually large lachrymals, thus shutting out the 

 orbito-sphenoids from articulation with the frontals. It is difficult to ascertain 

 whether the orbito-sphenoids are distinct. Their position is judged of by the fora- 

 mina. The line between the ali- and orbito-sphenoids seems to be marked by 

 a wide fissure, the foramen lacerum anterius, and just above this is a groove 

 extending obliquely downwards and backwards across the alisphenoid and ter- 

 minating in a foramen. It is not clear whether this is the foramen rotundum or 

 not. The exact position of the foramen opticum is difficult to ascertain, owing to 

 a slight displacement of the bones by lateral pressure ; it seems to be above 

 and slightly anterior to the sphenoidal fissure. The lachrymals are perforated 

 on the inner side of the orbit by two foramina ; on the outer side, just above the 

 maxillary suture, they are marked by a deep pit. 



UINTATHERIUM MIRABILE. 



The skull which has, upon conjecture, been referred to Uintatherium {Dino- 

 ceras) mirabile (Marsh) is quite distinct in contour from the corresponding por- 

 tions of the skull of either U. Leidianum or L. galeatus. It is represented by the 

 posterior half, the break having occurred just in front of the posterior protuber- 

 ances and extending vertically downwards. The distinctions arise first from the 

 smaller size ; it may be the head of a younger animal, but, as the teeth are wholly 

 wanting, there is no means of ascertaining this. A second and more striking 

 variation is in the shape of the posterior protuberances, Avhich are well pre- 

 served ; they are low and tuberous at the summits, barely rising two inches 

 above the marginal ridge, and presenting the usual transverse oval in section. 

 The marginal ridge of the parietals rises high behind them to a point about level 

 with their summits, so they do not form a conspicuous feature of the skull as 

 in U. Leidianum. The backward prolongation of the temporal fossa is also 

 marked. The occiput resembles that of L. Speirianum on a smaller scale, except 

 that it is less narrowed above the condyles ; it spreads widely above, and is 

 directed obliquely backwards. The surface is slightly concave from side to 

 side, with a median vertical crest for attachment of the ligamentum nuchce, 

 which is less pronounced than in Loxolophodon. 



Partial Descriptioti of Skull. — The base of the skull is in beautiful preservation, 



