160 The American Geologist. September, 18W 
comparing the shells of the beautiful, symmetrical thrifty- 
looking specimens from Saint Helena with those of the starved, 
impoverished, deformed specimens from Sioux City and Au- 
burn. In the ease of the globigerine forms that during most 
of their lives float near the surface, the condition of the bot- 
tom was not a matter of so much moment. The water at the 
surface was doubtless clear enough for their purpose, for even 
the small amount of sediment discharged into the sea by the 
sluggish, nearly base-leveled streams must have been limited 
to the lower strata of the water. Near the surface, too, food 
was doubtless even more abundant than it was at the same 
depth farther west, and thus it happened that near the shore 
the Globigerinre flourished, and their full grown shells, bear- 
ing every indication of life under most favorable conditions, 
settled down among the unhealthy and depauperated textulari- 
ans to which life had been a perpetual struggle with adverse 
surroundings. The shallow-water chalk contains large num- 
bers of shells of vigorous Globigerina? mingled with many small 
and deformed shells of Textularia?, while the deep-water 
chalk abounds in robust textularians with relatively few 
Globigerina?. Among the globigerine shells of the deeper 
water are a few rather remarkable monstrosities. 
Comparison with English Chalk. 
An attempt was made to compare our American chalk with 
that of England, but the opportunities for getting the desired 
number of examples from abroad were not good and the re- 
sults are not altogether satisfactory. Enough, however, was 
determined to demonstrate the presence in English chalk of 
the same species of Textularia and Globigerina that are so 
common along the Missouri ; there are closely allied species 
of Frondicularia, Bulimina, and Truncatulina ; there are also 
prisms from the outer layer of Inoceramus shells; while en- 
closing and imperfectly cementing together all the larger 
objects are minute, dust-like coccoliths that cannot be distin- 
guished from those making up so large a percentage of the 
deposits of the Niobrara. The conclusions so long ago reached 
by Ehrenberg and Baile} T * as to the identity of European and 
Missouri river chalk seem to be fully established. The water 
*Reports of the First, Second and Third Meetings of the Association 
of American Geologists and Naturalists, p. 357, 1843. 
