ARTICLE XIii. 
EXTINCT VERTEBRATA FROM THE JUDITH RIVER AND GREAT LIGNITE 
FORMATIONS OF NEBRASKA. 
BY JOSEPH LEIDY, M. D. 
THE present communication consists of descriptions, apparently of twelve new extinct 
species of fishes, saurians, chelonians, and mammals, from the territory of Nebraska. All 
of the fossil remains upon which these species are founded, with the exception of a single 
specimen, were discovered by Dr. F. V. Hayden, the zealous geologist and naturalist. The 
single specimen referred to, was obtained by Captain Alfred Sully, U. S. A., and was by 
him presented to the Academy of Natural Sciences of this city. 
Of the fossils collected by Dr. Hayden, those referred to, Z’rachodon, Deinodon, Paleo- 
scincus, Troodon, Crocodilus, Lepidotus, and part of those of 7rionyx were obtained from 
the vicinity of the Judith River, one of the tributaries near the source of the Missouri 
River. The other specimens were obtained from the Great Lignite Formation, considered 
to be of Miocene Tertiary age by Messrs. Meek and Hayden, and were collected by the 
latter gentleman, during an expedition to Nebraska, under the command of Lieutenant G. 
K. Warren, Top. Eng. U. S. A., by whose permission the author has examined and de- 
scribed them. 
The association of the remains of T’rachodon, Deinodon, Crocodilus and Lepidotus, cor- 
responding with the association of the remains of the closely allied Iguanodon, Megalosau- 
rus, Crocodilus, and Lepidotus of the Wealden Formation of England, led the author to sus- 
pect the Judith River Formation was of cotemporary age, though he was fully aware of the 
