Geology and Mineralogy. 831 
County overlying characteristic Trenton fossils; and (5) Hudson 
River slates, also conformably continuous with the precedin 
Professor Prime treats also of the origin of limonite beds associated 
with the damourite slates, and of other points in the geology of 
the region. His method of determin ning the age of the crystalline 
schists by means of oe fossils in the conformably associated 
strata Sts positive re 
Special Report on hee Tr ap-Dykes and Azoie Rocks of 
Seeithancerss Pennsylvania (E), by T. Srerry Hunt. Part I. His- 
torical Introduction. 254 pp. 8vo. 1878.—This Historical Intro- 
duction is a general exposition and re-statement of the author’s 
views on the “ Azoic,” Cambrian and Silurian rocks, of this and 
eruptive rocks, along with a historical account of former views on 
these and other subjects, wi a statement of the observations from 
various sources that appear to favor the views set forth. It is 
valuable as a definite exhibition of the present state of such views 
in the science, and of the arguments—not always just to the 
observations of others—by which they are sustained. The prog- 
ress of the science will show how much of truth there is in — 
ENsoN, M. <i Reap, AW V una, DWARD. RTON, 
Joun reas _F. C. H A.C. Linpemuta, J. T. Hopee and 
“ Herzer, with epglenniaed Reports by E. B. Anprews and 
. ORTON. 
From Professor Newberry’s Review we take the following 
conclusions. 
The Cincinnati group does not represent the Hudson River 
group of New York, but the whole pe — including the 
Trenton limestone and Hudson River gro 
in addition to sabe entire absene ce of Upper Silurian species, prove 
the wierrine to be much more closely allied to the Devonian than 
The “ Black shale” or “Huron shale” of the Devens! is made 
up of the black shales of the Lower Portage and the Gen In 
the shale, besides the gi gigantic Dinichthys, the jaw of a large 
nos sities has been obtained which has been referred to a new 
7 ipkighiaihide also a new _ of Dinichthys,a new 
Clenicocihtta and several of Clado 
