Microscopical Researches. 56 S 



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 tlie scene of dislocations or faults. 



MICROSCOPICAL RESEARCHES. 



The microscopic examination of fossil bodies was much enhanced 

 in value 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 JnfusoricB 

 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 iii seas 

 and estimries, were in existence when the cretaceous rocks were formed. 

 This announcement cannot but fail to ai'ouse the lively attention as 

 well as the surprise of geologists, who, relying upon what all the 

 otlier departments of palaeontology 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 i\\e 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 

 caution have been bestowed than he gave to the consideration of the 

 names for the subdivision of the Tertiary Series, as founded on a 

 great philosophical view. Whatever objections some persons might 

 entertain to the upper divisions of his system, the characters of which 

 were made to depend on a greater or less per-centage of existing 

 species, there could be little doubt, from the multitude of previous 

 researches, that his term " Eocene " was at all events secure from 

 criticism. Many practical geologists believed that the close of the 

 Secondary period was marked by some great agent of change, which 

 in modifying the surface was followed by the creation of new races 

 of animals. A few only argued that such a disruption or break 

 in the sequence of organic life must be a partial phenomenon, and 

 that as observations extended, we should find parts of the earth 

 wjiere transition strata of the supra-cretaceous age would fill up the 

 hiatus which seemed apparent between the chalk and the tertiary 

 strata over wide tracts of Europe. Such transitions, for example, it 

 was contended, were observed by Professor Sedgwick and myself 

 in the Austrian Alps, but the justness of our views was then combat- 

 ed by Boue, a geologist of great experience and research, wliilst M. 

 do Heaumont, M. d'Orbigny, and M. Michelin have since decided 

 against us, the first mentiuucd by a visit to the spot, the two others 



