STRATIGRAPHIC POSITION OF JUDITH RIVER FORMATION 749 
in the Hell Creek region and in Converse County, Wyo. Hatcher* 
says: 
The Trachodontidae had already attained to considerable diversity in 
Judith River times. Indeed they appear to have been more abundant as 
regards both numbers of individuals and genera and species than they were 
in the Laramie [Lance]. Judging from the rather meager material at hand 
for comparison, they were, however, somewhat less specialized. 
As to the Theropods, he says that so little is at present actually 
known from either the Laramie [Lance] or the Judith River beds 
' “that it is quite impossible to make anything like an adequate 
comparison between them. The group, however, is represented 
in both formations by quite similar forms, though differing perhaps 
both generically and specifically.” This statement appears to be 
little more than an assumption, inasmuch as about half the identi- 
fied species are common to both formations. Although as Hay 
says,’ much has yet to be learned of the Ceratopsia, especially of the 
Judith River forms, the knowledge of which is still somewhat vague, 
most of the remains from that region being of incomplete skulls. 
However, the interest in them has been so great that they have 
been studied with extraordinary care. This fact doubtless influ- 
enced Hatcher’s statement: ‘‘It is in the Ceratopsidae more than 
in any other group that we are at present able to contrast the Judith 
River and Laramie [Lance] forms.’ Hatcher’s conclusion based 
on this comparison is as follows: 
The primitive nature of the Judith River Ceratopsidae as compared with 
the Laramie [Lance] is especially seen in the smaller size of the individuals, the 
less perfectly developed armature of the skull, and the smperfectly developed parietal 
crest. 
The italics are Hatcher’s.4 This supposed contrast in the forms 
from the two formations is reiterated by Hatcher throughout his 
paper and in his monograph on the Ceratopsia edited by R. S. Lull 
and published by the Geological Survey.’ Osborn, in making the 
same contrast, comparing especially the nasal and supraorbital 
horns mainly of the species of Monoclonius and Ceratops (found in 
* Hatcher, op. cil., p. 102. 3 Hatcher, op. cit., p. 102. 
2 Hay, op. cit., p. 24. 4 Ibid., pp. 102, 103. 
5 Monograph U.S. Geol. Surv., XLTX (1907). 
