The purpose of this paper is to announce the discovery of fish remains in rocks of Ordovician age in the Bighorn mountains and to describe the character and relations of the rocks in which they occur. There will be added a few statements regarding the similar occurrence of fossil fish in the Ordovician sandstone near Canyon City, Colorado, announced by Mr C. D. Walcott in 1892†, and a brief review of our knowledge of the Ordovician geology of the Northwest.
The Bighorn mountains are an outlying portion of the Rocky Mountain range, extending from north-central Wyoming into the south-central portion of Montana. They rise abruptly out of the Great plains, which have an altitude of 4,000 to 5,000 feet, to altitudes which range from 10,000 to slightly over 13,000 feet in the higher mountain summits. The portion of the range to which . . .