BROfilE — GEOLOGY OP GLOUCESTERSHIRE, 
291 
truncaUim, whole blocks being nearly entirely composed of them ; and 
several beds of oysters were also obtained in situ at different depths. 
It is to be observed further, that the bivalves preponderate over the 
gasteropodous univalves iu the Lias generally, and in this particular 
zone are several species which are limited to it. The Cephalopoda 
(Ammonites, Bclemuites, and Nautilus) are not in this division repre- 
sented by so many species as in others ; although individuals are 
numerous, and indicate a considerable depth of water, llemains of 
Saurians are scarce, only a few bones and detached vertebra) of Plesi- 
osauri having been met with ; presenting thus a wide contrast with the 
abundance of those marine monsters in the lower part of this for- 
mation. 
In our next article, when describing the underlying beds, which, in 
fact, compose the main mass of the Lias in Gloucestershire, we hope to 
dwell somewhat longer on the habits and structure of the remarkable 
marine reptiles which played so prominent a part in the zoological 
history of the earlier stages of the deposit. Indeed, there is only one 
other geological period during which such creatures swarmed in equal 
profusion, and in such numbers that they must have been the tyrants 
of the deep, so that the eras of the Lias and Wealden have been not in- 
aptly termed the "age of reptiles." And, although these remains 
are few and far between in the upper and middle part of the series in this 
county, in other places they are much more frequent, as in the upper 
Lias at Ilminster, in Somersetshire, and at Whitby, in Yorkshire. 
Most people are probably aware of the general form and appearance of 
these saurians : a fine collection of them may be seen at the British 
Museum, and in various local collections, both public and private, so thai 
ample facilities are not wanting for making acquaintance with these 
extinct animals,* even to those who have little or no knowledge of 
Geology. ». 
Th2 gjirdens of tbo Crystal Palace arc enriclied with noble models of tUcfe 
creatures. — Ed. Geologist. 
