REVIEWS. 
419 
great lignitic formation, with its deposits of coal and iron. There are also 
evidences of considerable igneous action of recent date, as dykes are found 
traversing both the cretaceous and tertiary strata, altering the rocks through 
which they pass. Among the peculiarities of this basin of the Canadian is 
the terrace-like steps or benches — variable in height and distinctness of 
definition, according to the nature of the deposits — and which are the records 
of early shore-lines in the drainage of the ancient waters which occupied 
the region. 
Other portions of the district are also described, of which many interest- 
ing details of the geological and physical structure are given. The remaining 
papers of No. 3, which complete the second volume of the “ Bulletin,” 
comprise descriptions of some carboniferous and cretaceous fossils from 
Vancouver’s and Sucia Islands and other North-western localities ; a note 
on a singular cretaceous crinoid, apparently related to Marsupites, from the 
Neobrara group of the Upper Missouri ; and remarks on the geographical 
variation, especially as to size, among North American mammals. 
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