66 
Transactions Texas Academy of Science. 
Cummins, W. F. 
Neither it nor its congener in Euroipe has ever heen reported from the 
Jurassic. 
^‘Ostrea quadri/plicata, >Shumard, is very numerous in the Washita divis- 
ion of the 'Cretaceous, and has never been found elsewhere. The 0. crenu- 
linaryo, Roemer, which is a very similar though specifically distinct form, 
comes from a lower division. 
‘‘Trigonia emoryi, Conrad, has been found in the Washita division of the 
Cretaceous. 
“Gardium hillanum, iSowerby. This fossil has been reported frotm the 
Washita division. 
“Cytherea leonensis, Conrad, is a Cretaceous fossil found only in the 
Washita division. 
“Turritella seriatim granulata, Roem., is a Cretaceous fossil described 
from the .Fredericksburg division. 
“Oryphcea intclieri, 'Morton, ranges from the middle of the Fredericks- 
burg division to the top of the Washita division. This fossil is so different 
from the G. d/ilatata, var. Tucumcmd, Mar,, that notwithstanding they are 
found in the same bed, there was not the slightest difficulty in distin- 
guishing one from the other. 
“The only representative of the fossil flora we found was in the sandstone 
above the bed of blue clay, bed ‘F’ of Marcou’s section. * * 
“This single specimen, taken from ithese beds, even if there was no other, 
is sufficient to establish the fact that the strata are no older than the Cre- 
taceous, dt is true that, as a general thing, the whole of a flora or fauna 
of strata ought to be examined before one can say definitely the age to 
which the strata belong, yet there are eases when the sub-divisions may be 
definitely determined by a single specimen. This matter is so clearly stated 
by Lester F. Ward in a late paper that I quote the following extract: 
“ ‘The great types of vegetation are characteristic of the great epochs in 
geology. This principle is applicable in comparing deposits of widely dif- 
ferent ages where the stratigraphy is indecisive. For example, in rocks 
that are wholly unknown even a small fragment of a carboniferous plant 
proves conclusively that they must be Paleozoic, or a single dicotyledonous 
leaf that they must be as late as the Cretaceous,’ 
“While the Jurassic and Cretaceous are not widely separated, and both 
are in the Mesozoic, yet some of the plants are so widely different that a 
single specimen would be sufficient to determine that the age was no 
earlier than the Cretaceous.” Pp. 208-209. 
Coal Fields of Texas.^^ 
Manufacftnrers^ Eeeord, 'Baltimore^ Mare'll 10, 1893, pp. 112- 
113. 
This article is mainly a criticism of Professor Hill’s statement regard- 
ing “The Coal Fields of Texas,” as published in the Mineral Resources 
of the United States for 1891 (Washington, 1898), and reprinted in the 
above journal for Jan. 13, 1893. 
