COPE.] PALEONTOLOGY MIOCENE PERIOD. 489 



tinuous gentle concave plane, which is narrowed behind and widened in 

 front to support the bases of the horns. A postorbital process. Orbit 

 well developed, not reinarkablj^ anterior ; nasals elongate, transversely 

 plane, decurved, slightly emarginate at end. Premaxillary prominent, 

 with distinct spine, and extending as far as the line of the end of the 

 nasals. Squamosals not expanded. First premolar small ; canine 

 narrow. 



Measurements. 



M. 



Total length of cranium, (27 inches) 0.686 



Total width, including zygomas 433 



Width between temporal fossae at iuion 102 



Width in front * 247 



Width of orbit 102 



Length of horn above orbit 122 



Length of horn above nasals 045 



The horns of this species, though stout, are less formidable as weap- 

 ons than those of some of the others. 



At one locality teeth and a few other fragments of a very large indi- 

 vidual were discovered, and a few feet distant a series, of cervical and 

 dorsal vertebrae of appropriate size. A little further oft', in an opposite 

 direction, a- portion of the skeleton of a 8. hucco was found, with the 

 characteristically expanded zygomatic masses. It is not unlikely, how- 

 ever, that the vertebrae really belong to the S. trigonoceras. They indi- 

 cate an animal of huge proportions, and present a marked feature in the 

 enormous length of the neural spines of the dorsals. These are com- 

 pressed at the end and enlarged at the summit, indicating that the ani- 

 mal supported a hump, somewhat as in the bison. 



Measurements. 



M. 



Length of crown of fourth upper premolar 0.050 



Width of crown of fourth upper premolar 065 



Length of cervical vertebrse., (to base of ball) 060 



Depth of articular face behind !► !14 



Width of articular face behind 110 



Diameter of cervical canal 024 



Diameter of vertebral canal 065 



Length of centrum of dorsal to ball 065 



Depth of articular face behind 108 



Width of articular face behind Ill 



Depth of base of diapophysis 070 



A peculiarity of the dorsal vertebrae consists in the presence of two 

 tuberosities at the base of the articular convexity, resembling the artic- 

 ular facets for chevron-bones, but at the opposite end of the centrum. 



Beside the above, six more or less complete crania were found, and 

 two others without horns and otherwise mutilated, so as to render it 

 uncertain whether they do not belong to the S. ophryas. These exhibit 

 some range in size ; one of them presents the following — 



Measurements. 



M. 



Total length of skull, (30 inches) 0.762 



Length to orbit 172 



Length to posterior base of horn 280 



Width at zygomas, (17 inches) 432 



Height of horn above orbit 127 



Length of free part of nasal bones 127 



Width of base of nasal bones 133 



Width of horn on autero-exterior face 120 



Width between temporal fossae posteriorly 260 



Width between apices of horns, (17 inches) 4o2 



