246 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [March 24, 



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 

 diiferences, 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. Uppee Cketaceous. 



A. Red lacustrine limestone of VitroUes {Etage Garumnien of Leymerie). 



B. Dordonian Stage. Freshwater at Fuveau with Jjychnus. Marine in the 



Charente and Algeria. 



C. Campanian Stage (=: Upper Clialk). 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 Ceetaceotjs. 



F. Provencian Stage (with Sippurites). 

 G". Mornasian Stage (Uchaux Sandstone). 



H. Angoumian Stage {Radiolites cormi-pastoris). 



I. Ligerian Stage, with Inoceramus jprohlematicus and labiatus. ( = Inferior 



Lower Chalk.) 

 J. Carentonian Stage, with Ostrea biatiriculata and SphcBrulites foliaceus. 

 K. Gardonian Stage (lacustrine, with coal). 

 L. Rhotomagian Stage, with Turrilites costatus ( = Upper Greensand and 



Chalk Marl). 

 M. Gault. 



III. Lower CEETACEors. 



N. Upper Aptian Stage (=Argiles a PHcatules = Speeton Clay). 



W Middle Aptian Stage, with OrUtoUtes lenticularis ^ / j^^^^j. areensnnd). 



N . Lower Aptian Stage (= Vigoman) J ^ ' 



O. Neocomian Stage, with Spatangus reiusus. 



P. Valongian Stage, with Natica Leviathan ( = Weald). 



