160 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Etymology. — Junius, younger, in allusion to its small 

 size. 



Present determination. — From the two teeth (p4 and 



part of ma) preserved it appears that this species 



probably pertains to the genus Mesatirhinus. It is 



smaller than Mesatirhinus megarhinus. No other 



material has been certainly identified with it. (See 



p. 388.) 



Palaeosyops laticeps Marsh, 1872 



Cf. Limnohyops laticeps Marsh, this monograph, page 311 



Original reference. — Am. Jour. Sci., 3d ser., vol. 4, 



p. 122, August, 1872, dated "July 18, 1872" (Marsh, 



1872.1). 



Type locality and geologic horizon.— NesiT Marsh's 



Fork, about 15 miles from Fort Bridger, Wyo. A. H. 



Ewing, discoverer. Level not recorded. 



Holotype. — "A__nearly complete skeleton" (Yale 



Mus. lioOO). 



Etymology. — latus, broad; caput (in compounds ceps), 

 head; in allusion to the width across the zygomata. 



Present determination. — Marsh's accurate diagnosis 

 of this excellent type was made before the generic 

 characters of Palaeosyops were fully known. The 

 species was subsequently chosen by Marsh as the 

 type of the genus Limnohyops Marsh, and both the 

 genus and the species are valid. 



Telmatherlum Marsh, 1872 



Cf. Telmatherium, this monograph, page 340 



Original reference. — Am. Jour. Sci., 3d ser., vol. 4, 

 p. 123, August, 1872 (Marsh, 1872.1). 



Type species. — Telmatherium validum Marsh. (See 

 pp. 160, 344 of this monograph.) 



Generic characters. — See T. validum (p. 340). 



Etymology. — reXfia, a pool, marsh (cf. "paludosus"); 

 dripiov, beast. 



Figure 92. — Marsh's type of Palaeosyops laticeps 

 Natural size. 



Characters. — Marsh writes : 



The teeth in this specimen have apparently the same general 

 structure as those in the type of P. paludosus but differ in 

 being nearly smooth, and this is not the result of age, as this 

 individual was younger than the original of the larger species. 

 The proportions, moreover, given for the molar described 

 (Leidy, 1870.2, p. 113), "22 lines fore and aft and 18 trans- 

 versely," would not apply to any of the series in the present 

 specimen. The last upper molar of the latter has two well- 

 developed internal cones. * * * The upper teeth form a 

 complete series. The canine is large and broadly oval at its 

 base. The outer incisor is the largest, and at its posterior 

 edge the premaxillary is subtriangular in transverse section. 

 The sagittal and occipital crests are strongly developed, and 

 the coronoid process of the lower jaw is short and recurved. 



Measurements [Marsh] ^ 



Millimeters 



Length of entire upper molar series 155 



Anteroposterior extent of three true upper molars 94 [90] 



Anteroposterior diameter of last upper molar 36 [33] 



Transverse diameter [protocone to mesostyle] 40 



Anteroposterior diameter of upper canine at base 



[alveolar portion 28] 29 



Transverse diameter 22 



Present determination. — The generic term as re- 

 defined in the present monograph is a valid one. 



Telmatherium validus Marsh, 1872 

 Cf. Telmatherium validum, this monograph, page 344 



Original reference. — Am. Jour. Sci., 3d ser., vol. 4, 

 p. 123, August, 1872; dated "July 18, 1872" (Marsh, 

 1872.1). 



Type locality and geologic horizon. — "Near Henrys 

 Fork of the Green River in Wyoming." (Bridger 

 Basin, level C or D.) J. F. Quigley, discoverer. 



Holotype. — "The greater portion of a skull, with 

 teeth" (Yale Mus. 11120). (See fig. 93.) 



Characters. — Marsh writes: 



The dentition of this genus, so far as known, appears to be 

 similar to that of Palaeosyops; but the two may readily be dis- 

 tinguished by the anterior portion of the skull, which in the 

 present genus has the premaxillaries compressed, with an 

 elongated median suture. The zygomatic arch is also much 

 less strongly developed, and the squamosal portion of it is com- 

 paratively slender. 



