852 The American Naturalist. +  [October, 
the fossil vertebrates of the United States were neglected and 
left to the few who had cultivated the requisite knowledge to 
deal with them. 
Another reason existed for the tardy attention to Vertebrate 
paleontology, which continued till nearly the last quarter of 
our present century in the United States. No deposits con- 
taining many fossil vertebrate remains had become known in 
the east. Zoologists interested in the past and in the geneal- 
ogy of existing forms lamented the poverty of the United 
States, which contrasted with the richness of some parts of 
Europe. It was even thought that there was no hope of find- 
ing here such trophies of the past asthe beds of the Paris 
Basin or those of Grecian Pikermi had yielded to European 
paleontologists. But all this was to be changed. Rumor had 
long before hinted that numerous skeletal remains could be 
found incertain parts of the wild west, but the information was 
very vague. Enough was known, however, to induce Professor 
Marsh to visit certain deposits of which he had heard. In 1870 
he explored an Eocene lake-basin in Wyoming, drained by 
the Green River, the main tributary of the Colorado, and there- 
in found numerous bones, belonging to almost all parts of the 
skeleton, of some remarkable gigantic mammals which he 
called Dinocerata. The results of this exploration interested 
Cope in the highest degree. He visited the same region in 
1872, and thenceforth his attention to the Vertebrate paleon- 
tology of the western States and Territories was never inter- 
rupted. An intense rivalry arose between Professor Marsh 
and himself which, in time, it must be confessed, became very 
bitter. Nevertheless, as in most quarrels respecting facts, in- 
vestigations were provoked by mutual recriminations which 
resulted in a more speedy accumulation of data and a more 
critical examination of those data than would have been likely 
under less perturbed conditions. Most of those data relate to 
morphological and anatomical considerations, and therefore 
belong rather to mammalogy and herpetology than to geol- 
gy- 
The relations of the ancient forms to each other in point of 
time; to those of other lands, and to those whose remains 
