1895.] Geology and Paleontology. 1089 
species, and already at the base of the Uinta proper (Diplacodon elatus 
beds of Osborn) it exhibits a considerable variety of forms. Aside 
from the two species already known, there are indications of still 
others, one of which is shown in the pair of nasals (No. 11213) repre- 
sented in the outline drawing, Fig. 1, with the same portion of D. 
emarginatus, Fig. 2, drawn to the same scale introduced for compari- 
son. Notice the greater absolute and proportional breadth of the 
former, also the more pronounced medial emargination. 
1 
4 
Fig. 1. Sup. view of nasals Fig. 2. Sup. view of nasals of 
of Diplacodon, sp. } nat. size. Diplacodon emarginatus. } nat. size. 
If we compare Diplacodon with Telmatotherium vallidens, we shall 
meet with much more consistent results, for in this species we have all 
the conditions which we should expect to find in the ancestor of Dipla- 
codon from the Washakie beds. In T. vallidens the sagittal crest is 
already disappearing, the anteroposterior dorsal aspect of the skull is 
slightly concave, the zygomata are expanding and becoming stronger, 
the nasals are becoming broader and shorter, there are incipient fronto- 
nasal horns, and there are none of those inconsistent characters so 
numerous in T. cornutum. The Bridger representative of this series 
was doubtless Paleosyops laticeps, which has the concave dorsal aspect 
of the skull, broad zygomata and short nasals, all characters indicative 
of T. vallidens. 
In conclusion, there seems little doubt that the Parallel Series, I and 
II, established by Earle in his late paper, were differentiated early in 
the Bridger, and that Series I, of that author, was terminated in the 
Uinta, most likely by T. cornutum; while Series II was continued on 
up into the White River and terminated in the genus Titanotherium. 
Figures 1, 2, 3 and 4, Plate XX XIX, are introduced to show the suc- 
cessive stages of development from the Bridger to the base of the 
White River beds. Future discoveries will doubtless close the gaps 
