602 TIMOTHY WILLIAM STANTON 
are found indicate decidedly that the Trinity flora is not younger 
than the earliest stage of the Cretaceous. The number of plants 
found to be identical with certain of those of the oldest Potomac 
shows that there is little difference in the age of the two formations. 
The plant-bearing portion of the Trinity is somewhat older thanthe 
basal Potomac strata, but the difference in age cannot be great.”’ 
In this reasoning it seems to me that too much stress is laid 
on negative evidence, the absence of angiosperms. The present 
habits and distribution of plants do not warrant the assumption 
that a small collection containing only twenty-three species from 
a very limited area would necessarily include all the important 
types of plants living at the time they were entombed. The 
still more striking incompleteness of the Lower Cretaceous 
faunas will be discussed beyond. It will be remembered that the 
Kootanie flora and the plants from the Shasta, which were also 
compared with the Potomac flora, likewise showed the absence of 
dicotyledons and this was true even in the Horsetown beds 
which are known from their fauna and stratigraphic position to 
be far above the base of the Lower Cretaceous. 
Among the plants from the Washita horizon in southern 
Kansas, Dr. Knowlton" has recognized seven species of which 
five are dicotyledons and two are conifers. The species identi- 
fied had before been found only in the Dakota group ina flora 
usually assigned to the Cenomanian. It has been shown by 
Cragin,” however, that a part of the beds referred to the Dakota 
probably belongs to the Comanche series. At all events it is 
certain that the upper part of the Comanche approaches the 
Upper Cretaceous in character and it probably is not far from 
the horizon of the uppermost Potomac beds. 
The vertebrates obtained from the Comanche series are few 
and mostly fragmentary. The descriptions and determinations 
of Williston,3 Cragin,¢ and Cope’ show the presence of fishes, 
*In a paper by Mr. HIL1, Am. Jour. Sci. 3d. ser. Vol. L, 1895, pp. 212-214. 
?Am. Geologist, Vol. XVI, 1895, pp. 162-165. 
3 Kansas Uni. Quarterly, Vol. III, 1894, pp. 1-4. 
4 Colorado College Studies, Vol. V, 1895, pp. 69-73. 
5Jour. Acad. Nat. Sci. Phila., Vol. IX, 1895, pp. 443-447. 
