ON THE ORTGIN OR GEE /CnOuUREAULRAUINA: 
IN a recent number of the JOURNAL OF GEOLOGY appeared an 
interesting paper discussing the Chouteau fauna of southern 
Missouri and its relations to the geographical conditions of the 
region in which it lived and to the other faunas living before it 
appeared." 
Although personally acquainted with the careful work done 
by the author on this and associated faunas, having gone over 
much of the ground discussed in this paper with him, still I am 
not quite prepared to accept the author’s interpretation of his 
facts. And it is because his conclusions seem in some degree 
to be based upon principles which I have defended in papers 
already published, that I feel called upon to state in particular 
my reasons for dissenting from two of the opinions there 
expressed. The first of these opinions is expressed in Mr. Wel- 
ler’s proposition that the Chouteau fauna of Missouri, although 
not identical with it, was contemporaneous with the Chemung 
fauna of New York (p. 916). The second opinion is the con- 
clusion, drawn from a comparative study of the genera and species 
of the fauna, that it arose from the mingling of two faunas, the 
one coming from the east, and represented in Devonian time by 
the Hamilton fauna of New York, and the other, the general 
Devonian fauna of Europe represented by the middle Devonian 
fauna of Iowa and British America. 
The first of these conclusions seems to be consistent with, 
and but an extension of views advanced by me regarding the 
shifting of fauna.? But in order to speak of a fauna as moving 
from place to place and as occurring in one place above or below 
*A Circum-insular Paleeozic Fauna, by STUART WELLER, JOUR. GEOL., Vol. III., 
PP-, 903-917. 
2Proc. Amer. Assoc. Adv. Sci., Vol. XXXIV., pp. 222-234, 1886, and Amer. 
Geol., Vol. X., pp. 148-169, 1892. 
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