304 W. D. MATTIIP:W the rKPnWCEOrS-TERTIARY PROBLEM 



(•ally valueless for exaet correlation. His attempt to show that there are 

 any common genera among the Ceratopsia hinges entirely on the identi- 

 tieation of a specimen from the Denver beds, identitied by Marsh as Cera- 

 toj)s montanus or some nearly allied reptile/*^ and stated by LuU^^ to be 

 "too fragmentary for accurate determination." 



It will be sufficient to say that the published lists of species identified 

 from both Judith Eiver and Lance are in large part based on material 

 too fragmentars- for exact identification and of no value in exact correla- 

 tion, as has been shown in detail by Mr. Hatcher, and that all that are 

 sufficiently characteristic and complete to be of use in this way show that 

 the "Judith River" of Cope's localities is of practically the same age and 

 facies as the Belly River.^^ 



The age of tlie Judith River, like any other problem in correlation, 

 must be settled by bringing all the evidence into conformity. It can not 

 be settled by balancing conflicting evidence and assigning more weight 

 to one than to another class of data. Doctor Peale's attempt to bring all 

 the evidence into conformity is undoubtedly right in principle, although 

 biassed in method. But his solution of the vertebrate evidence is impos- 

 sible of acceptance, especially in view of the recent researches in the 

 Belly River fauna. 



Correlation with the European Succession 



general dtscvssioy 



The dividing line between Cretaceous and Tertiar}- in England is 

 drawn between the uppermost beds of the chalk and the littoral and 

 "fresh-water" beds which overlie it — the Thanet sands and London clay. 

 But between these there is known to be a very considerable gap in time. 

 This gap is partly filled on the continent by various intermediate forma- 

 tions, the highest stage of the chalk, the Danian, being absent in the 

 English succession. While this is generally recognized as Cretaceous, 

 there appears to be a difference of opinion as to the position of the Mon- 

 tien of Belgium and its equivalents. De Lapparent and other writers 

 reckon it as the latest stage of the Cretaceous, while Dollo, Rutot, and 



lOAmer. Jour. Scl.. vol. xxxvi, 1888. p. 477. 



^1 Ceratopsia monograph, p. IH?,. As Doctor Toalo quotos and comments on the next 

 preceding sentence in this reference, he could hardly have missed seeing this statexiienf. 

 to which he makes no allusion, although it invalidates his whole argument on this point. 



"A recent note in "Science" hy Mr. r. H. Sternberg puts a new light on the evidence. 

 If his recollection of the stratigraphy is correct. Cope's Ceratopsia specimens came from 

 a formation underlying the Pierre, while most of his fragmentary material came from 

 the typical localities which Mr. Sternberg recalls as overlying the Pierre. The evidence 

 from fossil vertebrates would accord with this, although I do not think It in any way 

 confirms it 



