610 TRANS. OF THE ACAD, OF SCIENCE. 
in the intervals, the latter being closely crowded, especially 
near the margins of the plates. 
The Cidaris hemigranosus is an unusually large species. 
One of our specimens when perfect must have exceeded two 
and a half inches in height, and the transverse diameter was 
considerably greater. 
Form. and Localities—In the Washita Limestone form- 
ing the upper part of the Bluffs of Red River, Lamar County, 
and ten miles above the mouth of Kiamesha Creek. At both 
localities it is associated with Ostrea qguadriplicata. 
Notes on the Geology of Kansas and Nebraska. 
By Jutres Marcov. 
[Read June 20, 1859.] 
In my “Letter on some points of the Geology of Texas, 
New Mexico, Kansas and Nebraska” (Zurich, 1858), I say; 
that the brown sandstones on the Missouri near the mouth of 
Big Sioux River, containing dicotyledonous leaves, are ° 
h all Oli- 
entitled 
braska,” 
senia, which are Cretaceous, belong to the phate ttt 
and supposing that these Cretaceous genera Da 
de core than three quat- 
and, according 
to the principles of paleontology, the majority of g 
species should determine the age. omnes 
and Nebraska,” by Messrs. Meek and Hayden, 
all to that genus, but to the Tertiary genus Sassqjr 
he himself thinks, is near to Sassafras eect oe fi sil 
Sinigaglia in Italy. So that, according to Heer, al 
Metre 
