168 Bibliographical Notices. 
Limestone, St. Louis Limestone, Kaskasia Limestone, and the Coal- 
measures. These Mr. Hall “considered more important in the pre- 
sent state of our knowledge,’”’—the Lower and Upper Silurian forma- 
tions having been illustrated in Dr. D. D. Owen’s Reports on parts 
of Iowa and the neighbouring States, and the higher groups, espe- 
cially the Carboniferous Limestones, not having received so much 
attention. Twenty-nine elegantly engraved plates and numerous wood- 
cuts illustrate the fossils, among which Brachiopoda and Crinoidea 
predominate. 
This Report, as far as it extends, appears fully to meet the require- 
ments of the State-survey organized in 1855, and provides the citizens 
of Iowa with clear information respecting their lands. To geologists 
at large it is also a very valuable work, providing means of compari- 
son for extensive Palzeozoic districts of which previously there was 
little exact knowledge; and we may look forward to the second 
volume as being even still richer in ‘‘ comparative geology ;”’ for it 
will not only treat of the relations of the Paleeozoic rocks, with which 
Mr. Hall has had a life-long acquaintance, but also of the Secondary 
formations of the Western Territories, to the consideration of which 
the same eminent geologist will have brought cautious experience 
and dispassionate acumen. 
Second Report of a Geological Reconnoissance of the Middle and 
Southern Counties of Arkansas, made during the years 1859 and 
1860. By Davip Dae Owen, Principal Geologist ; assisted by 
Rosert Prerrr, Chemical Assistant; M. Leo Lrsquerrvux, 
Botanist, and Epwarp Cox, Assistant-Geologist. Philadelphia, 
1860. 
This Report completes the preliminary Geological Survey of Ar- 
kansas; the First Report, by Dr. D. D. Owen, published in 1858 (the 
result of explorations in 1857-58), having treated of the northern 
counties of the State. Our knowledge of the geology of this exten- 
sive tract of country has hitherto been very vague. One of the most 
western of the States, Arkansas has been one of the latest in being 
systematically surveyed by professional geologists. The Survey was 
placed in excellent hands; for few, if any, were so well acquainted 
with the soils and rocks of the central area of North America, tra- 
versed by the Mississippi, as the late Dr. David Dale Owen. Un- 
fortunately this gifted and energetic geologist has lived but long 
enough, and scarcely that, to take a general view of the geological 
structure of Arkansas, and to point out its chief features, mineralo- 
gical and stratigraphical. But this was no light task, even with the 
aid of the gentlemen mentioned above as his assistants, as well as 
Mr. Jos. Lesley, his topographical assistant, working with him as 
friends only can work—with zealous co-operation. In the sad duty 
of preparing for the press that portion of the Report which existed 
only in the form of field-notes at the time of Dr. D. D. Owen’s decease, 
his brother (Dr. Richard Owen) was cordially assisted by Messrs. 
