FLOOr..] 
FOSSILS. 
SI 
the London Clay of the Isle of Sheppey, where th.ey'are found in the 
cement-stones [Septaria), or picked up hy the children who gather 
copperas " {iron pyrites) for the vitriol works. 
The Fossil Shells {yiollasca) are divided into four groups. 
1. Lamp-shells (Brachiojjoda). 2. Ordinary Bivalves [ConcJiifera). 
3. Spiral Univalves [Gasteropoda). 4. Chambered Univalves {Cepha- 
lopoda) . 
Lamp-shells (Brachiopoda). Cases 2 and 3, Room YI. Those from 
the Tertiary strata belong to existing genera, and some to existing 
species; but others, lil^e the great Terehratula oi the Suffolk crag, are 
unknown in a recent state. The Chalk species are no longer living, and 
belong chiefly to the genera Terehratula, Thccidium, lUryiichonella, and 
Tereh-atella, of which all, excepting the last, appear to be verging 
towards extinction, or, are scantily represented by existing species. 
The Fossil Bivalves (Conchifera), and Spiral Univalves (Gas- 
teropoda), have been arranged in parallel groups, according to their 
£^eoloo-ical ao-e. 
TEETIAEY FOSSIL SHELLS. 
1. Xewee Pliocene. Table Case (11), Ptoom YL, contains a series 
of Shells from raised sea-beds and beaches in Scotland, Sweden, and 
North America : these shells are of a more Arctic character than those 
now living in the adjacent seas. Table Case (lOj contains a similar 
series from Sicily. 
2. Oldek Pliocene. Table Case (13), Pioom YL, contains Shells 
from the "Crag" of the eastern counties, of which more than half 
are still existing, either in British Seas, in the Mediterranean, or on the 
coasts of Norway and North America. 
3. Miocene, or " Middle Tertiary." To this period are referred the 
Shells from St. Domingo, Case (11), Eoom YI. ; and part of those 
collected by Sir C. Lyell in the Canary Islands and Madeira, 
Case (0.) 
4. Eocene Teetiaey, or London Clay and Paris Basin, Cases (4 and 
G), PiOom YI. Not any of these can be certainly identified with living 
Shells; and the species which they may resemble are now found at 
the Cape of Good Hope, the w^estern coast of South America, and other 
localities remote from those where the fossils have been found. 
shells of the SECOND.VEY STEATA. 
5. Chalk, Gault, and Green-sand (Cretaceous System). (Table 
Cases 1 and 2, Pioom Y.) The characteristic Shells of the Chalk are 
Inoceravii, related to the recent Pearl-oyster ; SpoiuhjU ; Scallops (Pec- 
ten), of peculiar form ; " Cock "s-comb " oysters, and species of Lima 
and Pleiirotomaria. One peculiarity of the Chalk Fossils, is the con- 
stant absence of the interior pearly layers of the shells, which have 
been removed subsequent to their imbedding. In the Green-sand 
strata, Triyonioi abound, and peculiar bivalves, of an extinct family {llip- 
puritidcB), related to the recent Chama. (Cases 2 and 3, Koom YI.) 
