210 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Present determination. — Subsequent research has 

 proved that this genus is a synonym of Menodus. It 

 is fully described on page 522. 



Symborodon torvus Cope, 1875 



Cf. Menodus torvus, this monograph, page 525, Figure 166 

 Original reference. — Pal. Bull. No. 15, p. 2, "issued 

 August 20, 1873" (Cope, 1873.2). 



FiGUEB 165. — Type (lectotype) of Bronluihenum gigas 

 Lower jaw, with nearly complete dentition. Yale Mus. 12009. After Marsh, 1876. One-sixth natural size 



Subsequent reference. — Report on the vertebrate 

 paleontology of Colorado, p. 486, 1874. The jaw 

 figured in Plate 2, Figure 1, is not the type of torvus 

 (Cope, 1874.2). 



Type locality and geologic Tiorizon. — Horsetail Creek, 

 Logan County, northeastern Colorado; Chadron for- 

 mation {Titanotlierium zone), level not ascertained. 



Ootypes. — Cope writes: "The present genus is 

 established on mandibular rami only, which can not be 



certainly associated with crania." These rami (Cope 

 collection. Am. Mus. 6365, 6345) are accordingly 

 CO types. In his "Report on the vertebrate paleon- 

 tology of Colorado" Cope says, "I append a de- 

 scription of the mandible, on which the species 

 Symborodon torvus was established." Careful com- 

 parison of Cope's original and subsequent descriptions 

 and measurements shows that the species 

 was established largely upon the lower 

 jaw (Am. Mus. 6365, fig. 166) which 

 is accordingly regarded as the lecto- 

 type. 



Etymology. — torvus, wild, grim. 

 Present determination. — The species is 

 now regarded by Osborn as belonging in 

 the genus Menodus. In size the type 

 is intermediate between M. Jieloceras and 

 M. trigonoceras. 



Miobasileus Cope, 1873 

 (Indeterminate) 

 Original reference. — Pal. Bull. No. 15, 

 p. 3, "issued August 20, 1873" (Cope, 

 1873.2). 



Subsequent references. — On some ex- 

 tinct 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); 

 U. S. Geol. Survey Terr. Rept. for 1873, 

 p. 490, 1874. 



Type species. — Miobasileus ophryas 

 Cope. (See below.) 



Generic characters. — Not separated 

 by Cope from specific characters. 

 (Seep. 201.) 



Established on a cranium with nearly com- 

 plete dentition but without mandibular ramus. 

 Head elongate, concave in profile from the 

 interorbital region to the supraoccipital crest. 

 This is transverse and concave, the posterior 

 borders of the temporal fossae extending behind 

 it. These fossae leave a narrow flat vertex 

 between them. Zygomatic arch stout and rather 

 deep; a strong postglenoid process. Nasal bones 

 very massive, their free portion elongate, 

 hornless. A massive horn core rising from 

 above each orbit, no superciliary angle or ridge. Orbit not 

 inclosed behind. Of molar teeth only Pm. 2, M. 3, pre- 

 served, the M. with two, the Pm. with one inner cone, and 

 two outer continuous crescents. The latter send inward to 

 one side of the cones a transverse ridge. Incisors and canines 

 unknown. 



Char, specif. — Front concave transverse just behind between 

 the horns. Latter massive and little compressed. Nasal 

 bones convex longitudinally and transversely, slightly rugose. 

 Transverse ridges of teeth with transverse expansions at their 

 inner extremity, being thus T-shaped. 



