170 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Eolotype and specific characters. — Scott and Osborn 

 write : 



In the Washakie beds is found a large species, about the 

 same size as P. vallidens Cope, which is provisionally referred 

 to Palaeosyops (P. hyognathus, sp. nov., Princeton collection. 

 No. 10273). This is represented by a lower jaw seven-eighths 

 as large as the type mandible of Diplacodon. [See fig. 105.] 



;-->;x..i4:: 



Figure 104. — Cope's type of Lainhdotherium brownianum 

 One-half natural size. 



As in the latter, the incisors form a close procumbent series; 

 the tips forming a gently arched line when seen from above. 

 The symphj'sis is extremely long (11 centimeters) and shallow; 

 the canines are rather small and semiprooumbent. The molar- 

 premolar series measures 24.5 centimeters, the last molar 

 measures 6.5 centimeters, the transverse measurement outside 

 of the canines is 9.6 centimeters; in Diplacodon elalus 

 the same measurement is 10 centimeters. Unfortu- 

 nately, the premolar crowns are broken; it is probable 

 that one or two of the premolars will be found to be 

 like the molars. The characters of the chin and sym- 

 physis are significant of close relationship to Dipla- 

 codon elatus. 



Etymology. — vs, boar; yvados, jaw; in allusion 

 to the forward-pointing lower incisors and 

 shallow mandibular symphasis. 



Present determination. — The species is valid. 

 The generic reference is to DolicliorTiinus. 

 (See p. 409.) 



Liitinohyops Marsh, 1890 



Cf. Limnohyops Marsh, this monograph, page 303 



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

 vol. 39, p. 525, 1890 (Marsh, 1890.1). 



Type species. — Palaeosyops laticeps Marsh 

 (Am. Jour. Sci., 3d ser., vol. 4, p. 122, 1872). 

 (Seep. 311.) 



Generic characters. — Marsh says: 



In 1872 the writer described a large mammal from the Eocene 

 of Wyoming under the name of Palaeosyops laticeps. As the 

 name Palaeosyops has since been restricted, this species must 

 be regarded as representing a distinct genus, which may be 

 called Limnohyops. In this form the last upper molar has two 

 inner cones, and in Palaeosyops, as now defined, there is only one. 



Etymology. — Xiixfrj, shore; vs, boar; &}//, face. 

 Present determination. — This is a valid genus and 

 species. For fuller descriptions, see page 303. 



Palaeosyops megarhinus Earle, 1891 



Cf. Mesatirhinus megarhinus (Earle), this monograph, 

 page 388 



.--''" "~\ Original reference. — Am. Naturalist, 



vol. 25, No. 289, pp. 45-47, 1 fig., Jan- 

 ;-''' uary, 1891 (Earle, 1891.1). 



\__,,— ,^ Subsequent reference. — Earle, A mem- 



oir on the genus Palaeosyops Leidy and 

 its allies: Acad. Nat. Sci. Philadelphia 

 Jour., 2d ser., vol. 9, pp. 320-329, pi. 

 10, fig. 2; pi. 11, figs. 4, 5, 1892 

 (1892.1). 



Type locality and geologic horizon. — 

 Washakie Basin of Wyoming; level unde- 

 termined, probably Uintatherium- Man- 

 teoceras- Mesatirhinus zone (Washakie A). 

 Type.— "A fine skull (No. 10008) in 

 the Princeton collection" (Earle). (See 

 fig. 106.) 

 Paratype. — Earle writes: 



There is also another portion of a skull (No. 10041), probably 

 belonging to this species, with the occiput well preserved, from 

 the Bridger proper [Earle, 1891.1, p. 45]. This paratype probably 

 belongs to a more advanced species of this genus. (See p. 388.) 



Figure 105. — Type (holotype) of Palaeosyops hyognathus 

 Incomplete lower jaw. Princeton Mus. 10273. After Earle, 1892. One-fifth natural size. 



Specific characters. — Earle writes: 



Cranium: The characters of this skull are quite unique 

 and depart widely from any of the species of the family that 

 I have examined. The general form of the skull is broad and 

 depressed. Its dorsal contour is very like that of Palaeotherium 

 crassum — namely, there is no frontal depression, which is so 

 characteristic of Palaeosyops paludosus, and the occipital 



