1852.) 191 
logical map, comprises in all about 50,000 square miles, nearly one half of 
which lies in lowa, and the other half in Missouri. From north to south this 
coal-field is over 300 miles, and from east to west about 200. 
This coal-field is shallow, hardly exceeding fifty fathoms, and the coal-bear- 
ing strata proper hardly 100 feet. It seems to be the attenuated part of the 
great coal-field east of the Mississippi. It contains some four to six workable 
beds of coal, which. in lowa, vary from two to five or five and a half feet. 
Towards the southern margin of this coal-field, in Missouri, there are beds of 
great thickness—20 feet or more—ofa character intermediate between cannel 
coal and asphaltum. 
The coal of this coal-field is all highly bituminous and most slaty in its struc- 
ture; very frequently presenting the woody fibre on tke surface of the natural 
joints as distinctly displayed as on charcoal. 
On the extreme south of this map will be observed, close to the southern 
margin of this coal-field, an uplift of magnesian limestone and sandstone of 
lower Silurian date, bordering on the lead region of Missouri, and to be-found on 
both sides of the Missouri river, between Tavern Rock and Marion; here the 
carboniferous and lower Silurian rocks, are in close proximity and much 
blended together. 
To the extreme west of the map, on the Missouri river, opposite the mouth of 
Floyd’s river, the green represents the cretaceous formation which extends 
west of the Missouri river towards the heads of the Cheyenne, Moreau and 
White rivers, where it is succeeded by that remarkable Eocene tertiary basin 
in the Mauvaises Terres of Nebraska, containing those interesting extinct races 
of fossil mammalia described by Dr. Leidy in the Memoir forming part of the 
geological report. 
Many important additions will be found to our geographical knowledge of the 
country, derived partly from drafts and astronomical observations made by the 
geological corps, and partly from the most recent linial surveys. 
For further particulars I beg to refer the members to the forthcoming geolo- 
gical report of the surveys of the region of country represented by this geolo- 
gical map. 
November 16th. : 
Vice-President BRIDGES in the Chair. 
A note was read from Mr. Hlias Durand, dated Nov. 15, 1852, accom- 
panying his donation, acknowledged this evening, of 109 autographs of 
Scientific and Literary men. 
Dr. B. H. Coates stated that he had been referred by a friend to a passage in 
page 136, of a work entitled “ The Unity of the Human Races, Proved to be the 
doctrine of Scripture, Reason and Science; by the Rev. Thomas Smyth, D. D. 
New York, 1850??—in which his name is cited, with those of several others, as 
that of an ‘opponent’ of the doctrine or dogma of the Unity of the Human 
Species; and this on the authority of the late Dr. Morton. Dr. Coates had no re- 
collection of the passage in any of the writings of his late honored friend just named, 
or of any other, in which such a statement had been made for him; and could only 
presume that Dr. Smyth has either misapprehended some expression in Dr. 
Morton’s books, or has quoted from memory without referring to the text. Dr. 
Coates hoped to be allowed to have placed upon record in the Proceedings of the 
Academy an explicit denial of the above allegation, having never held the opinion 
there implied as his. He acquiesces in what he believes to be the general 
judgment of most scientific men—the unity of the human species—without 
claiming to have formed an independent opinion; but he is not ignorant that 
some strangely marked varieties, as the Ethiopian, are of a very high antiquity. 
The proposition frequently combined with the above, that the origin of the 
