Bibliographical Notices. 165 
on a subject, and clear up that which was before shrouded in mys- 
tery.’ Herein lies the explanation of the utility of all field-observa- 
tions. 
Report on the Geological Survey of the State of Iowa. By James 
_ Haxu (State-Geologist) and J. D. Wurtnry (Chemist and Mi- 
neralogist). Vol. I. Part 1. Geology; Part 2. Paleontology. 
Towa, 1858. 
In 1812 was published (in the ‘ Journal de Physique’ for February) 
the first geological map of the United States of America, by William 
Maclure; and this was improved and republished at Philadelphia in 
1817. Other independent observers, among whom were A. Eaton, 
L. Vanuxem, 8S. G. Morton, I. Lea, G. W. Featherstonhaugh, and 
W. Darby, continued to advance the knowledge of the geology and 
paleontology of the United States until about 1835, when consider- 
able impetus was given to geological research by two circumstances : 
—firstly, Murchison’s elucidation and arrangement of the Silurian 
strata, and the consequent clear systematization of the Paleeozoic 
rocks in Europe and America ; and secondly, the institution of spe- 
cial geological surveys by the Governments of several of the States of 
the North American Union and by the Federal Government itself,— 
the national importance of geological maps and reports having been 
recognized by the United States and by the English Governments at 
about the same time. 
The geological surveys of the following States were commenced 
about this period :—Maine (C. T. Jackson), New Hampshire (C. T. 
Jackson), Vermont (Z. Thompson and C. B. Adams), Massachusetts 
(E. Hitchcock), Rhode Island (C. T. Jackson), Connecticut (C. U. 
Shepard and J. G. Percival), New York (W.W. Mather, E. Emmons, 
L. Vanuxem, J. Hall, J. E. Dekay, L. C. Beck, and T. A. Conrad), 
New Jersey (H. D. Rogers), Pennsylvania (H. D. Rogers), Delaware 
(J. C. Booth), Maryland (J. T. Ducatel), Virginia (W. B. Rogers), 
Ohio (W. W. Mather), Tennessee (G. Troost), Indiana (D. D. Owen), 
and Michigan (D. Houghton). Most of these State-surveys have 
been prosecuted with vigour by the geologists above named and 
others, and have been productive of good maps and memoirs, and of 
valuable collections and descriptions of fossils and minerals. Sub- 
sequently the State of Kentucky was preliminarily examined by 
L. P. Yandell and B. F. Shumard in 1846, and geologically surveyed 
by D. D. Owen in 1854-55; and Missouri has been reported on by 
G. C. Swallow. The States of Wisconsin, Minnesota, Iowa, and 
Illinois were geologically explored by D. D. Owen in 1839-52; 
Wisconsin by the late J. G. Percival in 1854; and Iowa was more 
specially surveyed by James Hall and J. D. Whitney in 1855-57, 
and the results of their labours are published in the Report before 
us. Previous to making any remarks on this work, we may mention 
that in the Southern States geological surveys have been established, 
—in North Carolina (D. Olmsted and E. Emmons), South Carolina 
(M. Tuomey and O. M. Lieber), Alabama (M. Tuomey), Georgia 
