and we perceive that, as regards the faunas, and the development and number of the strata, the transitions are made insensibly. If, instead of adhering in this case to observations made step by step, we were to take long strides, and if from any part of Europe we were suddenly to find ourselves in India or in the United States of America, we should meet with much more embarrassing gaps.
I must not, however, forget to add that, in spite of very important differences, there exist, both in India and in the United States, a certain number of fossils which may be called characteristic in the highest degree, which are found everywhere at the same level, and which allow us to place the entire fauna in its proper arrangement, — whence we come to the conclusion that it would be illogical, as regards palaeontological stratigraphy, to consider any given country an obligatory and inflexible term of comparison, and to refer to it the formations of other countries. This would be to wish to establish arbitrarily a sort of bed of Procrustes, which would place us under the necessity of stretching or mutilating our subjects at every moment, in order that we might always obtain the same measurements.
It appears more reasonable to look at things from a higher point of view, and to regard a formation with its stages as a confederation composed of a variable number of cantons, united by common ties, rather than as a people springing from the same source, speaking the same language, and governed by the same laws and the same formulae.
TABLE OF STRATA AND EXPLANATION OF THE DIAGRAMS.
I. Upper Cretaceous.
A. Red lacustrine limestone of Vitrolles (Etage Garumnien of Leymerie).
B. Dordonian Stage. Freshwater at Fuveau with Lychnus. Marine in the Charente and Algeria.
C. Campanian Stage (=Upper Chalk). Freshwater at Fuveau with seventeen beds of coal ; elsewhere marine.
D. Santonian Stage (= Superior Lower Chalk). Upper part, freshwater at Fuveau.
E. Coniacian Stage (Sandstone).
II. Middle Cretaceous.
F. Provencian Stage (with Hippurites).
G. Mornasian Stage (Uchaux Sandstone).
H. Angoumian Stage (Radiolites cornu-pastoris).
I. Ligerian Stage, with Inoceramus problematicus and labiatus. ( = Inferior Lower Chalk.)
J. Carentonian Stage, with Ostrea biauriculata and Sphoerulites foliaceus.
K. Gardonian Stage (lacustrine, with coal).
L. Rhotomagian Stage, with Turrilites costatus ( = Upper Greensand and Chalk Marl).
M. Gault.
III. Lower Cretaceous.
N. Upper Aptian Stage (=Argiles a Plicatules = Speeton Clay).
N'. Middle Aptian Stage, with Orbolites lenticularis (= Lower Greensand).
N". Lower Aptian Stage (= Vigonian)
O. Neocomian Stage, with Spatangus retusus.
P. Valongian Stage, with Natica Leviathan ( = Weald).
