MEMOIR OF EDWARD D. COPE. 407 
most valuable memoir, which must long serve as a standard of reference 
in this particular department. For a considerable period Cope regarded 
the Sheridan beds and the older cave faunas of the east (Megalonyx 
beds) as Pliocene; but later he revised this opinion and referred them 
all to the Pleistocene, a change which is unquestionably right. 
In addition to this great body of investigations upon the geology of 
the western interior region, Cope made many important contributions 
to the geology and paleontology of the Atlantic coast; but in the latter 
case the material with which he had to deal was very fragmentary, and 
the results are in consequence less conclusive. 
Among Cope’s most valuable contributions to geology was the work 
which he did in correlating the various fossiliferous horizons of North 
America with those of Europe, a work for which his extraordinarily wide 
and accurate knowledge of the successive vertebrate faunas of both con- 
tinents especially fitted him. Of late it has become rather the fashion 
to deprecate as premature all attempts at correlating American and Euro- 
pean formations and even to deny the possibility of making such corre- 
lations in any trustworthy way. From the strictly geological point of 
view such a conservative attitude is natural enough ; but Cope did not 
regard the question from a purely geological standpoint. He was, above 
all things, a zoologist, and his principal lifework lay in tracing the origin, 
phylogenies, and relationships of animals, their migrations and geograph- 
ical distribution, and he clearly saw that such determinations could not 
be successfully undertaken unless the order of successive appearance of 
the various animal types in the-different continents could first be estab- 
lished. To this end geological correlations of widely separated deposits 
are an indispensable necessity, and a false correlation is better as a work- 
ing hypothesis than none at all, for it sets up a definite thesis in place of 
vague surmises. In this determination of the equivalences between the 
fresh-water Tertiaries of North America and those of other continents 
Cope was a pioneer, and while not all of his correlations have stood the 
test of fuller knowledge, many of them have only grown stronger with 
the advance of time and stand out as guide-posts in the further prosecu- 
tion of the work. For example, his correlations of the Wasatch with the 
Suessonian of France and of the White river with the Oligocene of 
Ronzon have been abundantly confirmed by discoveries undreamed of 
when the equivalences were first suggested. ‘The value of these deter- 
minations to the morphological paleontologist can hardly be overesti- 
mated, and every investigator owes a debt of gratitude to Cope for his 
labors in this department of geology. 
Great as his genius undoubtedly was, Cope was not, even as an inves- 
tigator, perfect and free from every fault ; to usea gallicism, he had *‘ the 
LX—Buns. Gror. Soc. Am., Vor. 9, 1897 
