DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



211 



Millimeters 



Length from apex of nasals to occipital condyles (axial) 684 



Length from occipital cond3'les to femoris of palate 376 



Length from occipital condyles to end of palatine lamina 



pteryzoidea 270 



Length of four last molars 242 



Length of three last molars 195 



Length of last molar 68 



Width of palate at nareal notch 116 



Etymology. — Mio, Miocene; /SacriXeiis, king — that is, 

 monarch of the Miocene. 



Present determination. — -The genus is indeterminate. 

 (See M. ophryas.) 



Miobasileus ophryas Cope, 1873 

 (Indeterminate) 



Original reference. — Pal. Bull. No. 15, p. 3, "issued 

 August 20, 1873" (Cope, 1873.2). 



Subsequent references. — Cope, On some extinct types 

 of horned perissodactyls, p. 108, 1874 (Cope, 

 1874.1); Synopsis of new Vertebrata from the 

 Tertiary of Colorado, p. 14, 1873 (Cope, 

 1873.3) ; Report on the vertebrate paleontology 

 of Colorado, p. 490, 1874 (Cope, 1874.2). 



Type locality and geologic Jiorizon. — Cedar 

 Creek, Logan County, Colo.; Chadron forma- 

 tion {Titanotherium zone), level not ascertained. 



Type. — A cranium with incomplete dentition, 

 without mandibular ramus. (In a later descrip- 

 tion Cope (1874.2, p. 490) remarks, "of molar 

 teeth only pm 3-4, m 1, 2, 3, preserved. ") This 

 type was left in the field and is now lost. 



Generic and specific cJiaracters (summarized 

 from Cope). — Supraoccipital crest concave. 

 Zygomatic arch stout and relatively deep. 

 Nasal bones very massive, elongate, convex 

 longitudinally and transversely; a massive horn core, 

 little compressed, rising above each orbit. In a later 

 communication Cope (1874.2, p. 491) gives the length 

 from apex of nasals to occipital condyles as 664 

 millimeters and observes: 



The dental characters of this species ally it to the S. trigo- 

 noceras, but the form as well as the position of the horns is 

 quite different. Instead of being triangular, a section of the 

 base of these is elliptic. Extremity conical. 



Millimeters 



Length from apex of nasals to occipital condyles 684 



Length of three last molars 195 



Length of last molar _. 68 



Etymology. — 64>pvs, eyebrow*; possibly in allusion 

 to the form of the orbit. 



Present determination. — Owing to the loss of the 

 type and the uncertain character of the description, 

 this genus and species is indeterminate. 



Megaceratops Cope, 1873 



Original reference. — Pal. Bull. No. 15, p. 4, "issued 

 August 20, 1873" (Cope, 1873.2). 



Present determination. — This name Megaceratops was 

 not proposed in order to denominate a new genus but 

 was merely an emendation on etymologic grounds of 

 Leidy's term Megacerops, of which it must be regarded 

 as a synonym. 



Megaceratops acer Cope, 1873 

 Cf. Megacerops acer, this monograph, page 545 



Original reference. — Pal. Bull. No. 15, p. 4, "issued 

 August 20, 1873" (Cope, 1873.2). 



Subsequent reference. — Cope, Report on the verte- 

 brate paleontology of Colorado, p. 488, pi. 7; pi. 8, 

 fig. 3, 1874 (Cope, 1874.2). 



Type locality and geologic Jiorizon. — Horsetail Creek, 

 northeastern Colorado; Chadron formation {Titano- 

 therium zone), level not ascertained. 



Type. — "A single cranium without under jaw." 

 Am. Mus. 6348. (See figs. 167, 170.) 



Figure 166. — Type (lectotype) jaw of Symhorodon torvus 

 One-sixth natural size. 



Specific cJiaracters. — Cope writes: 



Top of head flat, forming a narrow plane between the temporal 

 fossae; latter produced backward. Orbit not inclosed behind, 

 an overhanging superciliary ridge. Nasal exceedingly short 

 and massive, each supporting a large acute horn core, which is 

 connected with its fellow by a ridge at the base and diverges 

 widely from it with an outward and forward curve to the 

 acutely compressed apex. Each horn core about 1 foot long. 

 The top of the head is plane between the orbits, and little 

 concave fore and aft. The zygoma is very deep, and the post- 

 glenoid process well developed. End of nasal bones short and 

 thick but flat. 



Measurements 



Millimeters 



Length of cranium (35 inches) 895 



Length from posterior rim temporal fossa to middle of super- 

 ciliary ridge 345 



Width front between eyebrows 210 



Length horn core on inner side (10 inches) 254 



The elemental origin of the horn cores is probably different 

 in this genus from that which exists in Miobasileus. 



Etymology. — acer, fierce, in allusion to the somewhat 

 ferocious appearance. 



Present determination. — This valid species, which 

 pertains to the genus Megacerops, is fully described on 

 page 545. 



