i at la 
Mee 
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SHUMARD—CRETACEOUS STRATA. 589 
characters of the beds are strikingly similar. That they can 
not be older than the Cretaceous is satisfactorily shown by 
the fossils above enumerated. 
With regard to the Nebraska equivalent of our Arena- 
ceous Group, I think there can scarcely be a doubt that it 
represents No. 1 (perhaps the upper part) of the section of 
Messrs. Hall, Meek and Hayden. 
These authors have already pointed out the parallelism of 
A, B, C and D, of the Pyramid Mt. Section, with No. 1, of 
their Nebraska Section. ‘ 
e have not yet succeeded in finding in the Texas sand- 
stones and subordinate marls impressions of dicotyledonous 
leaves, which Meek and Hayden have found so characteristic 
of the sandstones occupying the base of the Nebraska Cre- 
taceous, and which Dr. Newberry has discovered in such 
abundance and perfection in the equivalent beds o the 
western slope of the Rocky Mountains ;* but it is almost cer- 
tain they will be found in this position in Texas. 
the formation. The best exposures of the group are 
Grayson, on Post-Oak, Choctaw, and Big Mineral Creeks, 
where sections of from fifty to sixty feet have been meas- 
ued. It occurs also on Red River, Fannin and Lamar 
counties. The estimated thickness of the group in this part 
of the State is about one hundred and fifty feet; but we have 
hot seen the base of the formation.” 
Fossils are extremely abundant in the septarie and nod- 
ules, and so far as I have been able to learn they belong to 
fitherto. undescribed species. From the collections of Dr. 
a Shumard, I have been able to characterize the ollow- 
&: Ammonites Swallovii, A. inequiplicatus, A. Meckianus, 
‘aysonensis, Ancyloceras annulatus, Scap 
peat Baculites gracilis, Cytherea Lamareni: cae i r 
1 ape ; 
“0 lean gregaria, Nucula yy eee ri cams 
wbulus, and Inoceramus, n. sp. Fossil wood is also quite 
* See Dr. Newberry’s hi : : on the Ancient Vegeta- 
i ‘saa y’s highly interesting paper 
Hon of N, A., in the March caaiber of Silliman’s Journal. 
