The Xiobrara Chalk. — Calvin. 149 
establish its physical identity with much of the English chalk. 
In the second place, one-needs only the cheapest of compound 
microscopes to demonstrate that it is surprisingly rich in the 
most perfectly preserved specimens of Foraminifera that in a 
large number of cases are specifically the same as those so 
long known in the chalk of Europe. In the third place, a 
better microscope will show that every cubic inch of the Nio- 
brara chalk contains many millions of the minute circular or 
elliptical, disk-like bodies called coccoliths, which cannot be 
distinguished from similar bodies occurring in similar num- 
bers and in similar relations in typical chalk on the other 
side of the Atlantic. 
Some References to Literature in which either the Chalky 
( iiahacteh oh Foraminiferal Okioin of the Ntobkaka 
deposits is recognized. 
In view of the widely prevalent impression that the Ameri- 
can Cretaceous contains no chalk, some references to the lit- 
erature in which the chalky character or foraminiferal origin 
of the beds in question is recognized may not be without 
interest. In the American Journal for 1841* Prof. J. W. 
Bailey describes the sample of "prairie chalk" already noted 
as being very rich in beautiful forms of the "elegantly little." 
The "elegantly little" are Polythalamia (Foraminifera) and of 
these he gives four excellent figures which, although un- 
named, are readily recognized as common species composing 
a large proportion of typical chalk, whether we collect it in 
England or along the Missouri river. In the same note it is 
stated that professor Bailey has also found very interesting 
forms of Polythalamia in the specimens collected by .Mr. .1. Kf. 
Nicollet from the "far west." 
In 1843 Ehrenberg published his Memoir mi tin Extent "ml 
Influence of Microscopic Life in South and Worth America. 
Most of the work is devoted to diatoms and desmids, hut ;i 
few pages are given to the discussion of Koram ini t'era. includ- 
ing forms from the Cretaceous chalks and marls along the 
Missouri river. The abundance of foraminiferal species and 
the identity of some with species occurring in the chalk of 
Europe are among the facts established. 
*Loc. cit. 
