186 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Etymology. — incisivum, provided with incisors; in 

 allusion to the great size of the superior incisors. 



Present determination. — The species probably repre- 

 sents a genus distinct from Telmatherium (see p. 353) 

 named Sthenodectes by Gregory. 



Type. — A skull lacking the posterior portion 

 (Carnegie Mus. 2888). (See figs. 131 and 132.) 

 Specific characters. — Douglass writes: 



The skull is high, the forehead broad, and the zygomatic 

 arches spreading. The premaxillary region as seen from the 

 front is broad, though the incisors are only moder- 

 ately large. The canines are directed outward. The 

 free nasals are short and moderately broad. Appar- 

 ently the infraorbital foramen is not excessively large. 

 The malar is rounded beneath the orbit and has no 

 protuberance or shelf. The zygomatic arch is not 

 very heavy and is only moderately deep anterior to 

 the glenoid articular surface. It is not nearly so 

 heavy as in Telmatherium uliimum. The opening 

 of the posterior nares extends forward to the middle 

 of the second molars. Their border is rounded and 

 thickened. 



The incisors are moderately large but not cupped. 

 They are arranged in an oblique line about halfway 

 between a transverse and anteroposterior direction. 

 The crowns of i' and i^ are low. The anterior faces 

 are very convex. There are two posterior flattened 

 surfaces separated by a rounded ridge. There are 

 no cups, but the posterior portion forms a kind of 

 ledge or keel. P is higher and is directed more down- 

 ward. The posterior portion is flattened, and there is 

 a low flat ledge behind the conical cusp. The canine 

 has a moderately high curved crown, on which there 

 are antero-internal and postero-external ridges, pass- 

 ing downward from the base to the apex. There is 

 also a narrow postero-internal ledge. 



Unless the skull is more crushed laterally than it 

 appears to be, there is a sudden contraction posterior 

 to the canine, so that the first two premolars are 

 much nearer to the median line of the palate than are 

 the canines. The diastema between the canine and 

 p' is about 3 centimeters in length. 



P' is a simple oblong conical tooth, which has a 

 small antero-internal depression, and a small ridge 

 passes backward from the apex to the posterior por- 

 tion of the rudimentary keel. P 2, 3, and 4 have low 

 cusps. The teeth increase nearly uniformly in width 

 and size from p^ to the last molar. The two outer 

 elements in each are well defined and are subequal 

 in size, although the anterior cusp is slightly the 

 larger. The internal cusp on p^ is small, oblong 

 anteroposteriorly, and is placed far back. The inter- 

 nal cusp on p' is much larger and is crescent-shaped. 

 On p* it is more nearly conical. There are rudi- 

 mentary cingula on the inner faces of the last three 

 premolars. The postero-internal cusp on m' is repre- 

 sented by a low crescent-shaped ridge. 



FiGUBE 129. — Type (holutype) skull of Telmatherium? incisivum 



palatal view; A3, 



Carnegie Mus. 2398. After Douglass, 1906. Ai, Superior view; 

 view. One-fifth natural size. 



Manteoceras uintensis Douglass, 1909 



Cf. Manteoceras uintensis Douglass, this monograph, page 372 

 Type reference. — Carnegie Mus. Annals, vol. 6, No. 



2, pp. 307-310, text figs. 4, 5, pi. 13, fig. 4, 1909; 



"issued November 6, 1909" (Douglass, 1909.1). 

 Type locality and geologic horizon. — Uinta Basin, 



Utah, about 5 miles northeast of well 2, from "gray 



sandstone in red Uinta beds. Lower portion of 



horizon C." Diplacodon-Protitanotherium-Epihippus 



zone (Uinta C) . 



Measurements [Douglass] 



Millimeters 



Is, lateral Lgjjgth of skull, anterior portion to glenoid 430 



Length of dental series 356 



Length of molar-premolar series ^-_-- 247 



Length of premolar series 106 



Length of molar series 141 



Transverse diameter of i' 16 



Anteroposterior diameter ofii 18 



Transverse diameter ofi^ 16 



Anteroposterior diameter of i^ 18 



Transverse diameter of i' 20 



Anteroposterior diameter ofi^ 22 



Transverse diameter of canine 22 



Anteroposterior diameter of canine 26 



