744 A. €. PEALE 
tion, Mont.; and north of Musselshell, Mont. In addition to the 
Hell Creek specimens listed by Barnum Brown he collected Tricera- 
tops and trachodont dinosaurs south and southeast of the Yellowstone 
River in Montana, Wyoming, and the Dakotas. Throughout this 
general area also the various parties of the U.S. Geological Survey 
engaged in tracing the distribution of the coal formations during 
the past six years have brought in numerous vertebrate specimens 
of similar character, showing their wide distribution in the Lance 
formation. 
As noted on a preceding page, Hayden was unable to detect 
any material difference between the deposits of the Judith basin 
and those of the Fort Union, especially of the portion lying at the 
base of the latter in the Missouri River region extending to the 
eastward. Similarly all the earlier paleontological workers could 
not make any separation based on the vertebrate remains found 
in them and did not separate the Judith River beds faunally from 
the beds, that, at Long Lake, N.D., and along the Yellowstone 
River and several other localities, lie immediately below the undis- 
puted Fort Union. Cope also in his work in northeastern Colorado 
recognized that he was dealing there with beds identical with those 
of the upper Missouri River country, especially the reptile-bearing 
portion of the Fort Union.t As the area of exploration in the west 
widened, and collections, fragmentary as most of them were, 
increased, and admittedly insufficient and fragmentary as is the 
material from the Judith River basin, the more evident became the 
remarkable resemblance between the faunas from the beds now 
referred to the Lance formation and those of the Judith River beds. 
Undoubtedly this would have been still more evident had there 
not been a strong effort to differentiate them, due to a misappre- 
hension as to the supposedly vastly older age of the Judith beds 
as deduced from supposed stratigraphic evidence. The probability 
of the Judith River beds being of post-Laramie age on account 
of the stratigraphic position and the contained vertebrate remains 
is referred to by Cross.? 
™ U.S. Geol. and Geog. Surv. of Terr. for 1873, 1874, pp. 429, 430. 
2 Monograph U.S. Geol. Surv., XXVII, 239. 
