Geology : 285 
the stratified diorites of Lake Huron a dyke, comment is unnecessary. 
Mr. Marcon tells us that the labors of Messrs. Jewett, Billings, G. M. 
Hall, Perry, Farnsworth, Richardson, Bell and himself, have resulted in 
the collection of more than 1200 species of fossils from the Calciferous 
sandrock, Now the whole number of species yet described from this 
formation by Prof. James Hall, Vanuxem and Billings, including the 
Point Levis fossils, is not much more than 200. As for the additional 
1000 species, Mr. Marcou’s reiterated statement is either a mistake or a 
great exaggeration, though we do not doubt that farther researches must 
add to the fauna of these rocks. It will be noticed that in the lists of 
fossils given by Mr. Marcou, he does no more than make a display of the 
hames cited from Mr. Billings’s late published descriptions. 
A word about Sir William Logan’s sections, ai in the Canadian 
Section, Sir William makes no reference to Quebec; nor has he, as Mr. M. 
Would imply, anywhere described the Potsdam shales or the Black River 
“ ‘ 
same rock described by Sir William at its foot, and says “it is difficult 
for me ¢ i J f limestone could have eseaped my no- 
tice,” get rsigiees cates all the emphasis of italics, that “the 
re tion.” His visit to Montmorenci last. autumn however taught him 
, and he now tells us that the limestone “at the top of the ie and 
oy ce foot of the precipice, immediately in contact with the quartzite, are 
the Trenton li e age.” p.249. The italics this time ~ - ne 
~® Moreover says that in 1849, he erroneously considered the b 
