58 The American Geologist. .lan. i89o. 
the origin of veins, lines of contact where minerals may be 
looked for with probable success, and other matters such as 
faults, dykeSj etc., of equal interest and importance. There is reason 
to believe that mines and mining are regarded with more favor in 
Colorado than researches in paleontology. At all events the resfer- 
ences to fossil faunas are not always happy. For example, in speak- 
ing of the well known Carboniferous brachiopod, Spirifcra rocky- 
montana Marcou, there seems to be an unnecessary concession to 
unscientific readers at the expense of scientific accui'acy when it is 
described as "a sort of pectifeated cockle-shell with a groove down the 
middle of the shell; this is called a Spirifer (Spirifer Rooky-Mon- 
tana)." Fleurotomaria is in one place transformed into Pleuroto- 
Marift, while a little farther on, as if in expiation of previous reckless 
waste of capitals, the genus Inoceramus is written with a small i. 
On the whole, however, the work is a valuable one, and Prof. Lakes 
has rendered his fellow-citizens an abiding service in giving them a 
guide to the geological structure of Colorado and the distribution of its 
important mineral deposits at once so clear, so thorough and so 
reliable. Even the "scientific few" will find in it much to interest 
them. The work is finely illustrated with views, sections, etc., from 
the facile pencil of the author. 
Description of eight new species of fossils from the Camhro- Silurian, 
rocks of Manitoba. By J, F. Whiteaves. This paper constitutes a 
part of Transactions of the Royal Society of Canada, vol. vii. Section 
IV, 1889. Of the eight species here described, one is a gasti-opod, 
Maclurea manitobensis . The other seven species are Cephalopods. 
The Maclurea is one of the finest examples of the genus, some individ- 
uals attaining a diameter of eight and a half inches. Although the 
exact stratigraphical relations of the rocks from which the fossils were 
obtained have not been determined, they are yet on purely paleonto- 
logical grounds referred in part to the horizon of the Trenton lime- 
stone and in part to the Hudson River group. The Cephalopods 
taken by themselves, however, would certainly indicate a later period 
than any to which the species in question have been referred. Parallel 
generic differentiation did not occur among Cephalopods in the 
Mississippi valley until the late Silurian or early Devonian. Six 
plates illustrate the paper. 
The Geological and Natural History Survey of Minnesota, Seventeenth 
Annual Report, for the year 18SS. N. H. Winchell, State Geologist, pp. 
VIII and 270. The main body of this report is divided about equally 
into three parts, the first being a discussion of the stratigraphy of the 
Archtean and primordial formations by the state geologist, the second a 
report of field-work in the Archean iron producing district of northern 
Minnesota by Mr. H. V. Winchell, and the third a report of field-work 
on the Archean of northeastern Minnesota by Mr. Uly. S. Grant. 
There followsa bibliography of American publications since 1872 relat- 
