COPE.] PALEONTOLOGY MIOCENE PERIOD. 487 



and probably by several others, some of wliicb are nearly perfect. The 

 muzzle is shorter than in auy other, and the orbit iDore anterior. The 

 premaxillary and nasal bones are shortened ; the latter broad, obtuse, 

 and massive, aud standing on a plane above that of the front. The ver- 

 tex and front do not form a continuous concavity, as in other si)ecies, 

 but are divided equally by a tuberosity on each side; posteiiur to these 

 the vertex is flat aud rather wide, while the front anterior to them is 

 roof-shaped. The temporal fossae do not project so far behind the occi- 

 pital union as in some species, and the squamosal bone is not remarkably 

 expanded laterally. There is a small postorbital angle. The front 

 rises much to the basis of the horns. Each of these stands above the 

 orbit and face at the base, and one-third of each over orbit; face and 

 nasal bones above the latter. They are straight, with approximated 

 bases, aud but moderately divergent. They are subcylindvical at base, 

 and compressed inward and forward at the narrow apex. The maxillary 

 rises on the base, forming a squamosal suture on the anterior ajid lat- 

 eral aspect, opposite the nasal meatus, and below the nasal bones. 



The first premolar aud two incisors are very insignificant ; canines with 

 short, stout crown. The premolars have no inner cingulum, but two 

 smooth cones. The molars have only two inner cones, vrhich (Converge 

 toward the crescents. The latter do not give origin to any transverse 

 crests. 



3Ieasurements. 



M. 



Length of cranium, (25+ inches) 0.f)49 



Length of crowns of teeth from canine .444 



Length of true molars .240 



Length of last molar .083 



Width of last molar 084 



Width of first premolar .035 



Length of first premolar .026 



Lengfh of orbit 090 



Least -width of parietal plane .235 



Length of nasals from horns .045 



Width of nasals at horns .152 



Length of horn-core above orbit, (9 inches) .229 



Length of horn-core above nasal bones .140 



This is one of the most formidably-armed species, and must have pre- 

 sented a most outre appearance in life, owing to the extreme shortness 

 and elevation of the muzzle and anterior position of the orbit. The 

 general form of the cranium reminds one of a pack-saddle without the 

 h.iud cross-trees. 



I owe the discovery of the beautiful cranium, which represents the 

 sj)ecies, to the acuteness of my assistant, William G. Shedd. 



SYiVrBORODON HELOCERAS, Cope, Proceed. Amer. Assoc. Adv. Sci., 1873, 

 109 ; Synop. Xew Vert. Col., 1873, p. 14. Megacerato2)s heioceras, Cope, 

 Pal. Bull. No. 15, p. 4. 



Free portion of nasal bones as broad as long. Horn-cores mere tuber- 

 osities, with one flat outer, and one very convex, face pi^esenting in the 

 other directions; summit contracted, truncate, oval in outline. A dis- 

 tinct sui)erciliary ridge. The upper surface of the cranium rather nar- 

 row, gently concave longitudinally. Molar teeth with smooth enamel ; 

 the crescents not displaying the T-shai)ed branches seen iu >S. opJiryas, 

 Zygomas deep, flat, not expanded. 



