File:The Quarterly journal of the Geological Society of London (12961151215).jpg

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several unpublished species; and M. Peron, who has intelligently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