GEOLOGICAL SURVEY OF THE TERRITOEIES. 359 



specimens, I think it probable that most naturalists would have been 

 misled, and perhaps referred them to different genera. While I, am not 

 prepared to say that they may not indicate different species, all the 

 other teeth are so nearly alike, in form and size, that I am disposed to 

 "view them as the same. 



Different isolated specimens of teeth exhibit some range of variation 

 in size of individuals of Palceosyops, a variation which might lead one to 

 view the specimens as representing several species. 



Nearly all the remains of Falceosyops submitted: to my examination I 

 have referred to a single species, with the following name: 



Palceosyops paludosus. 



The size of the species was about that of the living Tapir of South 

 America. The length of the upper series of molar teeth is 5| inches 5 

 of the three true molars, 3^ inches. The length of the lower series of 

 molar teeth, in a specimen belonging to a different individual from that 

 from which the former measurements were taken, is 6^ inches ; the true 

 molar series is 3f inches. 



Prof. Marsh has described a tooth which he refers to a smaller 

 species, with the name of P. minor. I suspect, however, that the speci- 

 men really pertained to a smaller individual of the same. 



Palceosyops major. 



A large species of Palceosyops, about the size of the Indian Ehinoceros, 

 is inferred to have existed, from a few imperfect fragments obtained, in 

 the vicinity of Fort Bridger. They were discovered by Dr. Carter the 

 last summer, and were presented by him to the Academy of Natural 

 Sciences. In Palceosyops paludosus the lower three back molars occupy 

 a space of 3J inches; in the larger species, P. onajor, the same teeth oc- 

 cupy a space of 4J inches. 



Tkogosus. 



Among the fossils, from the Bridger Tertiary formation, brought to the 

 notice of the writer there is the lower jaw of a remarkable animal, which 

 would appear to be an odd-toed i)acliyderm allied with the Tapir, but 

 associating characters which approach it to the gnawing animals. The 

 specimen was discovered last spring, in association with remains of 

 Palceosyops and those of a curious extinct turtle, in the vicinity of Fort 

 Bridger, by Dr. J. Yan A. Carter, and was obligingly presented to me 

 by him. The jaw belonged to an aged animal, so that the usual distinct- 

 ive characters of the molar teeth are for the most part obliterated as 

 the result of attrition in mastication. The construction of the jaw, but 

 especially the cutting- teeth, are quite suificientto distinguish the animal 

 from all its associates as well as from any other previously described. 

 The number of molar teeth to the series is six if not seven, the imper- 

 fection at the fore part of the specimen not permitting of a more positive 

 determination. The molar series was not widely separated from the 

 front teeth as in the Ehinoceros, Mastodon, and the whole order of gnaw- 

 ers, but closely approached the position of the incisors, apparently so 

 as to leave no space to be occupied with a canine tooth, unless it was a 

 very small one. The true molars in their worn condition look as if they 

 were nearly identical in form with those of Palceosyops. 



The fore part of the lower jaw of Trogosus, or the Glnawing Hog, as ] 

 have named the animal, is Occupied with a pair of large incisors, some- 

 what peculiar, bub so nearly resembling the incisor teeth of the rodents 



