M. Alex. B rongniart sur les caracteres Zoologiques, &c. 217 
from Grodno and Keminiac—white chalk, full of flints and 
echinites from the castle of Cracow; in the neighbour- 
hood are found shells similar to those of the coarse lime- 
stone of Paris, and sub-Apennine mountains. _ 
4. Green Sand or Glauconie crayeuse (crave chloriteé) de 
La Perte du Rhone, near Bellegarde. There are here two 
very distinct formations. 1. The inferior, a fine, grey, yel- 
lowish, compact limestone, in regular, nearly horizontal 
strata, without any visible petrifactions. 1t however con- 
tains between its strata, as in Jura, beds of marl very differ- 
ent from the superior formation, to be described, and 
abounding in shells closely analogous to those in the 
marl beds of Jura; some are also analogous to shells in the 
marl bedsnear Havre. 2. The superior, a yellowish lime- 
stone often shaded with yellowish ochry veins, stratifica- 
tion distinct, nearly horizontal, with a slight dip S. E.; it 
seems to be made up of an immense mass of lenticular 
stones, which are found to be little madrepores, (orbitolites 
lenticulata; Lam.) Above are alternate strata of marly lime- 
stone, and a sandy clay mixed with green grains, (green 
sand.) This upper formation abounds in shells strikingly 
analogous to those of the green sand formation, particularly 
from Folkstone, and St. Catherine. The genera are the 
same; the species, some identical, and others distinguisha- 
ble only when laid side by side. There are no shells of 
more ancient or more recent formations, than that of chalk. 
Besides the analogy of fossils, this upper formation contains 
the green sand of the Glauconie, and rests upon a bed of 
pyritous marl like the Glawconie at Honfleur and Tesworth, 
Eng. The lenticular rock is so ferruginous as to be called 
an iron ore by Saussure; it is analogous to the ferruginous 
sand found below the green sand in England and Norman- 
dy. : 
oe Formation of the chalk period. in the chain of Buet, 
resting on rocks of the transition period. This chain pro- 
ceeds from the summit of Buet, in the Alps of Savoy, and 
consists of dark coloured summits, nearly perpendicular on 
one face, and sloping on the other, and very lofty ; (about 
$000 feet above the level of the sea.) 
On the top of one of these suminits, (in particular,) that 
of Fis in the valley of Servoz, is a rock which M. B. refers 
to the chalk formation. The inferior strata of the mountain, 
Vor. VIII.—No. 2 28 
