SCOTT : LITOPTERNA OF THE SANTA CRUZ BEDS. 1 7 



from the hinder margin of each a low tubercle, or spine, projects into the 

 temporal fossa. The postorbital process, which is long, broad and plate- 

 like, has a somewhat twisted appearance, due to the fact that for most 

 of its length the principal diameter is transverse, while at the distal end 

 the principal diameter is antero-posterior. The foramen for the frontal 

 artery is double and is placed rather more mesially than in the horse ; 

 another vascular foramen in each frontal is somewhat forward of and 

 internal to the first and may be either single or double ; from it a well 

 defined groove passes forward to the nasal. 



The nasals are very short, extending but a short distance over the pre- 

 maxillaries, and quite broad behind ; each is decidedly convex trans- 

 versely, with a deep groove along the sutural line, and for some distance 

 from the front end the two bones may be well separated. For nearly 

 half their length, the nasals are not in contact with the maxillary and this 

 free portion contracts rapidly to the blunt anterior point ; the fore part 

 of each nasal has a thin lateral border and a thick mesial border, making 

 the bone triangular in cross-section. 



The premaxillaries are quite rhinocerotic in shape ; they are short, broad 

 and heavy, with broad dorsal surfaces and short ascending processes, which 

 do not reach the nasals ; the palatine processes are relatively large, but 

 the incisive foramina are small. The maxillary is very large ; the sub- 

 orbital portion is low, but the preorbital, or facial, portion is very high, 

 especially in view of the entirely brachyodont dentition ; a short process 

 of the maxillary, between the premaxilla and the nasal, forms part of the 

 boundary of the anterior nares ; the small infraorbital foramen is situated 

 far in advance of the orbit, above the anterior part of p-^ and is constantly 

 double. The hard palate is long, narrow, contracting slightly forward, and 

 deeply concave transversely. The palatines are rather small, extending 

 to the posterior margin of p-, and the posterior palatine foramina are in 

 the suture between the palatines and maxillaries. The posterior nares are 

 also relatively small, with nearly parallel sides ; the anterior border is oppo- 

 site the middle of m-. The pterygoids, which are inconspicuous and early 

 fuse with the alisphenoids, have no fossae or hamular processes. 



The cranial foramina are quite characteristic and do not entirely agree 

 with those of either the artiodactyls or the perissodactyls. The optic 

 foramen and foramen lacerum anterius are near together and are enclosed 

 in a common, deep fossa ; the latter foramen is very large, especially in 



