1869.] 



COQUAND CEETACEOTJS STKATA. 



245 



on the Geology of Constantine, I have received from M. Brossard 

 several unpublished species; and M. Peron, who has intelligently 

 explored the high plateaux of the provinces of Algiers and Constan- 

 tine, has in his possession a great quantity of new materials, which 

 he intends to make known, and which must certainly he very im- 

 portant, judging from the large quantities of Ostrece which I have 

 received from him for a publication upon which I am now engaged. 

 In the chain of the Madonies in Sicily, I was able to recognize the 

 Ehotomagian type of the environs of Tebessa, represented by iden- 

 tical fossils of the same colour (Ostrea syjphax, Ostrea africana, 

 Ostrea Overwegi, Coq.). M. Seguenza also discovered the Ehoto- 

 magian stage in the Province of Reggio, in Calabria. We know 

 that it exists in the Lebanon, and in the desert which separates the 

 Dead Sea from the Eed Sea. 



From the foregoing details it appears that, should we continue to 

 take the English divisions as a frame- work for the general divisions 

 of the chalk, we shall find it insufficient to contain the enlarged 

 canvas. 



We have indeed seen that beyond the basin of Paris the chalk 

 of Mans is increased by a new stage (the Carentonian), the chalk of 

 the west by three stages (the Angoumian, Provencian, and Dor- 

 donian), and the chalk of Provence by the Mornasian stage. 



If we now endeavour to draw conclusions from the resemblance 

 or identity of the faunas, we shall see that, in addition to the fossils 

 which are common to all, and which form useful landmarks in the 

 field of discovery, each region possesses species peculiar to itself; 

 so that if we were to compare two extreme points, as, for example, 

 Algeria and England, without taking into account the intermediate 

 localities, we should be so struck by the great dissimilarities as to 

 ask ourselves whether we are not comparing two diiferent formations. 



Fig. 4. — Section of the Cretaceous Beds of Algeria. 



Tebessa. 



Dj. Osmer. 



Tenoukla. 



Jurassic. 



But if we compare Algeria with Provence, Provence with the Cha- 

 rente, the Charente with the Sarthe, the Sarthe with Paris, and 

 Paris with England, we recognize, without any surprise or shock, 

 the connecting links which unite the scattered particles into a whole. 



