WAUI> I 



HISTORICAL REVIEW OF OPINION. 419 



Professor Cope's article, from which we made quotations a few pages 

 back, appeared for the third time in his tiual report ou fossil ver- 

 tebrates' with very few changes. It is to be noted, however, that he 

 no longer proposes to call the lignite deposit the sixth member of the 

 Cretaceous formation of the West, and referring to the fossils from the 

 Milk Eiver district last mentioned we find him saying " that there are 

 present two genera in this collection which are diagnostic of the Fort 

 Union epoch, but no species certainly so, though two species are prob- 

 ably identical with species of that epoch ; also * » * that the species 

 referred to PInsiomenus constitute an indication of afilnity with corre- 

 sponding Eocene forms. The presence of gar fishes of the genus Clastes 

 in this formation is as yet peculiar to this and the Judith Kiver localities. 

 As these gars have not heretofore been found in North America below 

 the Eocene, they constitute the first case of apparent commingling of Ter- 

 tiary and Cretaceous animal life yet clearly determined." He is careful 

 to add, however, that the evidence of the Dinosaurs outweighs these 

 considerations. 



At this time, when at least one vertebrate paleontologist was begin- 

 ning to concede that this formation, though apparently Mesozoic, yet 

 possessed a marked Tertiary facies, Mr. John J. Stevenson came forward 

 with several papers ^ from the stratigraphical side in support of the 

 Cretaceous theory. His language is the most positive of any yet em- 

 ployed, but a careful examination of his statements shows that his 

 argument acquired its chief force from the form in which it was put 

 forward. Such statements as that " everywhere the sandstones of the 

 Upper Cretaceous present the same lithological character ;" that "not 

 a single Tertiary species occurs in the whole series ; " that " wherever 

 animal remains occur with this fucoid [Halymenites] they are invaria- 

 bly characteristic Cretaceous species ; " that " the evidence in favor of 

 Cretaceous age is abundant ;" that the record of plant life is "little bet- 

 ter than a blank, with here and there a few markings, many of which are 

 too indistinct to be deciphered ; " that " the only fossils characteristic of 

 No. 5 ever obtained from Colorado were procured from rocks which are 

 most probably the very highest strata of the Liguitic series"— would, if 

 the question were at all one of credibility, as it is not, clearly invalidate 



this witness and make his own charge, '^fahus in uno, falsus in omni- ^O^J ^^ j^M^^'^'^' 

 bus," peculiarly applicable to himself. Mr. Stevenson's writings, how- ^/ 1 1 i' 



ever, have the merit of defending the essential unity of all the liguitic \\u-&.»^ o~^^ 

 deposits. i/J-a,uIIUi 



1 Report of the United States Geological Survey of the Territories, Vol. II, 4°, 1875, (\J(_j,'^-»~^ ••' 



pp. 25-41. ^__ 



= Proceedings of the Society of Natural History, New York, 2d ser., No. 4, 1874, p. 93 ; tjl/yA^tUi'^ ' *^ 



Age of the Colorado Lignites, Reports upon Geographical and Geological Exploration / I i /^ 



and Survey West of the One Hundredth Meridiau, in charge of First Lieut. Geo. M. fltfl-^ VjJoldJf^ 



Wheeler, Vol. Ill, 187.5, pp. 404-410; The Geological Relations of the Lignitic Groups, it fVii !>.(' 



Proceediugs of the American Philosophical Society, Vol. XIV, pp. 447-475. ^^ /U^^"^^^ 



