4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 63 



that its upper part is slightly recurved. The surfaces of the upper 

 half are roughened and grooved by vascular impressions. 



On the tip of the left half of the nasal horn is a small, flattened 

 oval bony ossicle, which rests in a shallow depression or pit on the 

 apex of the horn as shown at os, figure i. This ossicle is a distinct 

 element from the underlying bone and may represent the incipient 

 horn of later Ceratopsians where it is known to be developed from a 

 center of ossification distinct from the nasal bones. 



'OS 



Fig. i. — Nasals and nasal horn cores of Brachyccratops montancnsis. Type : 

 Cat. No. 7951 U. S. Nat. Mus., Yi Nat. size. A, side view; B, front view; c, 

 surface for contact with the premaxillaries ; /, surface for articulation of pre- 

 frontal ; no. anterior nasal opening; os, ossicle on top of horn core; p, anterior 

 process of nasal ; po, orifice for superior processes of premaxillaries ; s, suture 

 separating two halves of nasal horn. 



The maxillaries are of triangular outline with alveoli for twenty 

 teeth in the functional row. As compared wath Triccratops this is 

 a greatly reduced number, Triccratops having forty alveoli in the 

 maxillary. In this specimen all of the functional teeth have fallen 

 out, but two or more germ teeth are still retained and these give 

 some idea of their character. 



