410 The American Geologist. june, isos 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
EUments <le PaUontologie, par Felix Beknard, Premidre pariie (pp. 
528) a.vec 26r, figures dans le texte. Paris,Bailliere et fils, 1893. The whole 
work will form a volume of 1,000 pages, with 600 figures in the text, at 
a cost of twenty francs. The work is not a mere corapend of previous 
publications, but aims rather to be a philosophical review of paleontology 
in the light of the theories of evolution, taking note of important 
memoirs, whether French or foreign, which have appeared up to the 
very moment of printing. Fossil forms are frequently compared with 
living species. This gives naturalness to the grouping and a fresh bio- 
logical aspect to the comparisons and conclusions. 
Opening with a brief statement of the relations of paleontology with 
the other sciences, the author falls into a very interesting "History of 
Paleontology," dating its actual foundation, as well as that of compara- 
tive anatomy, from the brilliant work of Cuvier. He divides the whole 
history into three periods: first, that which preceded Cuvier; second, 
the interval between Cuvier and 1857, a period characterized specially 
by descriptive details of extinct species; and third, from 1857 to the 
present, characterized by broader philosophical groupings, and by the 
rise of the "transformist school," or evolutionists. This period is 
marked by the most minute precision in its observations, the effort be- 
ing to derive from the organism all that it is possible to know of its 
morphology, its structure, and its development. It is in the realm of this 
period that the work of the author lies principally, and in the profound 
change which the science of paleontology has undergone since the vari- 
ation of species was recognized as a fundamental law he discovers the 
effect of the doctrine of evolution. Evolution and paleontology have 
mutually aided each other. 
In seeking for a definition of a species he shows, by reference to the 
researches of Hilgendorf on Planorbis, confirmed and extended by Hyatt, 
that numerous species could be founded on forms which were, it is true, 
very variable, but which were actually derivable the one from the other. 
The work of Waagen on Ammonites subradiatus resulted in the union 
of many apparently specific forms under the common name Oppelia. 
Waagen used the term "variation" when the differences were found 
in different localities from the same stratum, but "mutation" when they 
appeared at the same locality in different strata. Neumayr reached the 
same result in studying the Paludinasof the upper Miocene. From these 
works a new point of departure at once sprang up for paleontology. 
The immutability of species, taught by Cuvier, was disproved, and at 
the present time there is no possibility of defining a species. Each 
paleontologist erects his own standard. The grand purpose is now to 
trace lines of development, and as the author remarks, "such research 
