GEOLOGICAL SURVEY OF THE TERRITORIES. 145 



group of beds is destined to yield a fauna second only to that of the 

 "bad lands" of Dakota. So far as yet known, all the remains appear 

 to be of middle tertiary age. Among these fossils those of turtles are 

 especially numerous. A multitude of fragments, together with several 

 forms, nearly entire, have been collected and sent to Professor Leidy, 

 of Philadelphia, for examination. The specimens have been referred to 

 three extinct species; the greater number pertain to a fresh-water tur- 

 tle which has been named Trionyx guttatus. The genus to which it 

 belongs is found at the present time living in the rivers of America, 

 Asia, and Africa. It is represented in our country by the Trionyx fer vx, 

 or great soft shelled turtle of the Mississippi and its tributaries. The 

 animal is noted for its voracity and feeds on fishes, snakes, and young 

 alligators. Its ancestor of the Bridger tertiary period no doubt was 

 equally predaceous in its habits. ■ 



Another turtle, of which a nearly complete specimen was discovered, 

 ■was more like our marsh terrapins in character. It, however, belongs 

 to an extinct genus and species, to which Professor Leidy has given the 

 name of Baptemys Wyomingensis, from the habit which it no doubt pos- 

 sessed, in common with most of its tribe, of at least taking an occasional 

 plunge in some convenient bathing place. Some of the nearest living 

 relatives to this turtle are now found in Central America, the so-called 

 Dermatemys and Staurotypus of Vera Cruz and Tobasco. The third spe- 

 cies of turtle indicated by fragments Professor Leidy has referred to a 

 terrapin which he has named Emys IStevensonensis, in honor of James 

 Stevenson, the companion and able assistant of the author during his 

 geological explorations of the interior of our continent. 



From other fossil remains from the Bridger Group of rocks, Professor 

 Leidy reports the former existence of an animal presenting an affinity 

 to the hyena and panther. It was larger than our species of the latter, 

 and was evidently a predaceous animal of great strength and ferocity. 

 It has been named Patriofelis ultd, which signifies the ancestral cat that 

 hath revenged itself. The remains of a small animal discovered by Mr. 

 J. A. Carter, of Fort Bridger, and sent to Professor Leidy, were referred 

 by him to an insect-eater related to the European, hedgehog, to which 

 he has given the name of Omomys'Carteri, in honor of its discoverer. 



It will thus be seen that all the animals indicated by the fossils from 

 the Bridger bed, comprising three different turtles, a carnivorous and 

 an insectivorous mammal, are of species and genera previously unknown 

 to science. They, therefore, indicate an especial fauna, accompanied by 

 a peculiar flora, of which thus far we have seen but a trace. Further 

 researches will most probably give to us an interesting history of the 

 lost race of animals, of the former existence of which we now have an 

 intimation. Figure 13 presents a most excellent view of the "bad 

 lands" as seen on White Biver, Dakota. This illustration may be 

 regarded as a typical one of the style of surface erosion of the White 

 Biver and Bridger Groups. The original sketch was taken on the spot 

 by Mr. F. B. Meek in 1853, and is published by permission of Professor 

 James Hall, of Albany, New York. 



There are also beds of limestone, composed entirely of a small species 

 of Cypris which gives to the rock a beautiful oolitic structure. Of fresh- 

 water mussels, Unios, Goniobases, Viviparas, JPlanorbis, several species 

 are found at different localities. Sometimes the Goniobases and Unlos are 

 found on a slab of limestone in great numbers, filled with chalcedony. 

 All the evidence that we can secure, points to the conclusion that all the 

 sediments of the Bridger Group were deposited in the bottom of a purely 

 fresh- water lake, with no access to salt or even brackish water from any 

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