358 GEOLOGICAL SURVEY OF THE TEREITOEIES. 



SciUEAVus, Marsli. 



Sciuravus nitidus ; Sciuravus undans. 



Two rodents, about the size of tbe Brown Eat, and probably belonging 

 to the squirrel family, named by Prof. Marsh from some remains found 

 at Grizzly Buttes, Wyoming. 



ODD-TOED PACHYDEEMS. 



Pal^osyops. 



The most abundant of the mammalian, remains pertaining to the 

 Bridger Tertiary strata, judging from the fossils which have been brought 

 to our notice, are those of a tapir-like animal about the size of the living 

 Tapir of South America. It was first indicated by a few imperfect but 

 characteristic specimens discovered during Prof. Hayden's expedi- 

 tion of 1870. Since then it has been more fully exemplified by numerous 

 specimens, many of them in a fine state of preservation. Most of these 

 were collected during the last summer at Grizzly Buttes, Henry's Eork 

 of Green Eiver, Lodge-Pole Trail, and other localities in the vicinity of 

 Fort Bridger, Wyoming, by Dr. J. Yan A. Carter and Dr. Joseph K. 

 Corson, U. S. A., and by these gentlemen were partly presented 

 to the Academy of Natural Sciences of Philadelphia, and in part 

 obligingly presented to the writer or submitted to his examination. 

 Prof. Marsh has also informed us that his party had collected many 

 remains of the same animal in the same locality. 



The specimens clearly establish Palceosyops as an uneven-toed pachy- 

 derm, with the skeleton constructed nearly as in the Tapir. 



The thigh-bone possesses a third trochanter, as characteristic of the 

 odd- toed pachyderms, including the Tapir, the Ehinoceros, and the Horse. 

 The hind feet nearly repeat the construction of those of the Tapir. 



The skull, with its large temporal fossae, high aad thick saggital crest, 

 concave occiput, broad, convex face, resembled that of the related 

 Palceotherium of the Eocene deposits of Europe. The teeth also agree in 

 number and nearly in constitution with those of that animal. The num- 

 ber of teeth altogether appear to have been 44, consisting of 3 incisors, 

 1 canine, 4 premolars, and 3 molars to the series on each side, above and 

 below. The teeth in each jaw form a nearly unbroken arch, intervals 

 existing only sufficient to accommodate the passing of the points of the 

 large and bear-like canines. 



The true molars above and below have a resemblance to those of 

 Palceothermm. In the crown s of the ui^per true molars the inner constitu- 

 ent lobes are more completely isolated from the outer ones than in that 

 genus, and the bottoms of the transverse valleys are proportionately of 

 less depth. The last upper molar of Palceosyops has but a single lobe 

 to the inner -part of the crown. 



• In PalcBotJierium the large premolars have the same form as the true 

 molars, but are quite diflerent in this respect in Palwosyops. In the 

 former the crown of the upper premolars, except tbe first, is composed 

 of four lobes, as in the succeeding molars. In Palwosyops the first pre- 

 molar has a conical crown, the second has a bilobed crown, and the 

 third and fourth have trilobed crowns. 



The canines of Palceosyops are proportionately as large and of the 

 same form as in the Bears. These teeth render it probable that Palce- 

 osyops varied its vegetable diet with the flesh of animals. In two speci- 

 mens of upper jaAvs, containing complete series of molar teeth, the sec- 

 ond premolar teeth differ so much, that had they been found as isolated 



