168 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Type species. — LeurocepTialus cultridens Osborn, 

 Scott, and Speir. (See p. 341.) 



Generic characters. — Scott and Osborn write: 



Upper incisors acute, with strong posterior ridges, lower in- 

 cisors compressed and laniariform, canines compressed, with 

 serrated cutting edges; first upper premolar with rudimentary 

 anterior lobe, last upper molar with rudimentary postero- 

 internal cusp. Molars constructed as in Palaeosyops but higher, 

 with sharper cones and more erect external lobes. Internal 

 median valley very much deeper. Little or no depression at the 

 forehead; zygomatic arch round, comparatively straight and 

 does not project outward, and with obscure postorbital 

 process. Premaxillaries short and straight. Mandible with 

 nearly straight lower margin and shallow masseteric fossa; 

 mental foramen single. 



Etymology. — Xeupos, smooth; Ke(j>a\r], head; in 

 allusion to the smooth texture of the bone. 



Present determination. — LeurocepTialus is a synonym 

 of Telmatherium Marsh. 



Figure 101. — Type (holotype) of Leurocephalus cultridens 



Right prematiUa, maxilla, and mandibular ramus. Princeton Mus. IQ027. Atter Osborn, 187S. One-third 



natural size. 



Leurocephalus cultridens Osborn, Scott, and Speir, 1878 



Cf. Telmatherium cultridens (Osborn, Scott, and Speir), this 

 monograph, page 341 



Original reference. — E. M. Mus. Geol. and Arch. 

 Princeton Coll. Contr. No. 1, p. 42, pi. 4, 1878 (Osborn, 

 Scott, and Speir, 1878.3). 



Subsequent reference. — Earle, A memoir on the genus 

 Palaeosyops Leidy and its allies: Acad. Nat. Sci. Phil- 

 adelphia Jour., 2d ser., vol. 9, pp. 343-348, pi. 10, 

 tig. 3, 1892; type (Earle, 1892.1). 



Type locality and geologic horizon. — Henrys Fork 

 divide, near Fort Bridger, Wyo.; Vintatherium- 

 Manteoceras- Mesatirhinus zone (Bridger C or D). 



Holotype. — "Established on specimen having a 

 nearly complete dentition and portions of the cran- 

 ium" (Princeton Mus. 10027). (See fig. 101.) 



Specific characters. — The specific and generic char- 

 acters were not distinguished in the original descrip- 

 tion. 



Etymology. — culter, a knife; dens, tooth; in allusion 

 to the sharp-edged reciurved canines. 



Present determination. — This genus is a synonym of 

 Telmatherium Marsh. The species is valid. (See 

 p. 341.) 



Palaeosyops borealls Cope, 1880 ' 



Cf. Eotitanops horealis (Cope), this monograph, pages 156, 292 



Original reference. — Am. Naturalist, vol. 14, p. 746, 

 1880 (Cope, 1880.1). 



Subsequent reference. — Cope, Tertiary Vertebrata, 

 p. 703, pi. 58a, fig. 3, 1884 [1885], (Cope, 1885.1). 



Type locality and geologic horizon. — "Badlands in the 

 upper drainage basin of the Big Horn River in western- 

 central Wyoming"; Wind River formation, horizon 

 not determined, probably Lambdotherium-Eotitanops- 

 Coryphodon zone (Wind River B). J. L. Wortman, 

 collector. 



Holotype. — "Founded on a portion of the right 

 maxillary bone, which supports the three true molars 

 and one premolar" (Cope collection. Am. Mus. 4892). 

 (See fig. 102.) 



Characters. — Cope writes : 

 Size of Limnohyus fontinalis, or much 

 smaller than P. laevidens. Anterior median 

 tubercle well developed; anterior and pos- 

 terior cingula strong, not rising to inner 

 cones. A low ridge extending outward and 

 forward from posterior cone. Enamel 

 smooth. Differs from P. junior Leidy in 

 the presence of the intermediate tubercle 

 and crest and in the weak ex-ternal cin- 

 gulum. Length of true molar series 63 [mil- 

 hmeters]; diameters of first true molar, 

 anteroposterior, 19; transverse, 20. 



Etymology. — borealis, relating to 

 Boreas; in allusion to the Wind River 

 formation. 



Present determination. — The species 

 is valid but generically distinct from 

 Palaeosyops. It is the type of the 

 genus Eotitanops Osborn. (See p. 289 .) 



Lambdotherium Cope, 1880 



Cf . Lambdotherium Cope, this monograph, page 279 

 Original reference. — Am. Naturalist, vol. 14, p. 746, 



1880 (Cope, 1880.1). 

 Subsequent reference. — Cope, Tertiary Vertebrata, 



p. 710, 1884 [1885] (Cope, 1S85.1). 



Figure 102. — Type (holotype) of Palaeosyops borealis 



Right upper part of right maxilla with p<-m3. Am. Mus. 4892. After Cope, 



18S5. Natural size. 



Type species. — Lambdotherium popoagicum Cope. 

 (Seep. 281.) 



Generic characters. — Cope writes : 



Dentition much as in Limnohyus, excepting that there is a 

 diastema in front of the second inferior premolar. Presence of 

 first inferior premolar not ascertained. Fourth inferior pre- 

 molar without posterior cusps. Superior molars with an 



