657° 
sented greater obstacles. These data are indeed only more correct 
and more detailed illustrations of the general phenomena advo- 
cated by Bakewell, De la Beche, and the American geologists, that 
the recession is chiefly due to the water undermining soft shale and 
sand from beneath ridges of harder rock which are successively 
plunged into the abyss. It is well however to observe, that, from an 
inspection of the country, Mr. Lyell has modified his former view, 
that the letting off or bursting of the Lake Erie might be the ultimate 
result of the retrocession of the Falls, for he now seems to incline 
to the belief, that owing to the nature of the strata through which 
they will have to work back, the final result will be the formation 
of long and dangerous rapids; while he justly points out how the 
formation of canals and the demand of water for the use of the lower 
country, which is passing from a state of forest to one of cultivation, 
will cause a gradual diminution of the upper lakes, and thus prevent 
a future catastrophe. But the chief point of interest in this memoir 
seems to me to be the inference deduced from the oceurrence of 
beds of ancient fluviato-lacustrine shells near the top of the cliffs 
bounding the defile of the Niagara, and necessarily high above its 
present bed, that the river has worn down its channel through a tract, 
in which the former water-courses (probably a succession of lakes 
or lake rivers) flowed on a much higher level; and he gives a strong 
reason for believing that the river has been the chief agent in this 
denudation, by stating that the channel in which it flows is not in 
any part the scene of dislocations or faults. 
MICROSCOPICAL RESEARCHES. 
The microscopic examination of fossil bodies was much enhanced 
in yalue when D’Orbigny astonished us by its application to the 
smaller cephalopods or foraminifera of the tertiary and cretaceous 
rocks, and by presenting us both with valuable descriptions and en- 
larged drawings and models. The discoveries, however, of Ehren- 
berg, and the much higher magnifying powers employed by him, 
opened out as it were a new former world of life, when he proved 
that certain strata were almost if not entirely composed of JInfusorie 
so minute, that millions were included in a cubic inch of rock. In 
advancing his observations, this naturalist has recently asserted that 
certain species of animals of this class, which are now living in seas 
and estuaries, were in existence when the cretaceous rocks were formed. 
This announcement cannot but fail to arouse the lively attention as 
well as the surprise of geologists, who, relying upon what all the 
other departments of paleontology had developed, had come to the 
belief, that no form now living was created until after the completion 
of what are termed the Secondary rocks. If this discovery of the 
illustrious Prussian be substantiated, we see in it another proof, in 
addition to those which I have adduced in the previous pages, of 
the danger of as yet attempting to establish a nomenclature founded 
solely on the fauna and flora of former conditions of the planet. No 
terminology appeared less likely to be shaken than that proposed for 
the tertiary rocks by Mr. Lyell, nor could more time, thought and 
VOL, III, PART II. 3H 
