LIASSIC FOSSILS. 
407 
forms represented in oolitic strata, and are now restricted in this 
country to very few representatives. 
The Triassic system is not so well displayed in this country as in 
Germany, where the deposits are readily divisible into three sections, 
from whence arose the distinguishing name. It is mainly a marine 
formation, and characterized by the advent of siphonated Streptoneura, 
but otherwise resembling the Palneozoic era, as we know of no 
undoubted fossils of terrestrial mollusks therefrom in England. In 
its faunal aspect this formation has been compared to New Zealand 
and Madagascar at a comparatively recent period. 
The Jurassic system receives its name from the Jura mountains, 
where it is well displayed ; it shows a prevalence of the siphonated 
gastropods and also the advent of the Opisthobranchiate forms. 
It embraces the Lias and the Oolitic formations and has been con- 
sidered by Phillips to represent the organic aspect of Australia at 
the present day. 
The Lias, apparently a quarryman’s corruption of layers, is remark- 
able for the appearance of the Ammonites, which quickly attain a 
most remarkable development, and in this country for the advent of 
certain well differentiated genera of pulmoniferous Gastropods, not 
previously recognized in British strata. The known species recoi’ded 
from liassic strata are : 
V.\LV.\Tin.E. 
HELICID.E. 
Helix dawsoni ^loore. 
rui’iD.E. 
Vertigo murchisoncc Moore. 
LniN.EID.E. 
Planorhis viendipensis Moore. 
P.VLUDESTRlNin.E. 
Pcdudestrina solkbda (Danker). 
Valvcda anomala ^loore, 
pxjgmea Moore. 
nESP<ENID.E. 
Dcsjxena Igelli (Moore). 
NERITID.E. 
Neritinn arenacca Terq. , 
canal is Terq., 
hcttangiensis Terq. 
The Oolites (wov, egg ; At^^os, stone), so named on account of con- 
sisting of a mass of small rounded egg-like particles, are according to 
the classification adopted in England, divided into three sections : 
the Lower Oolites, the Aliddle Oolites, and the h pper Oolites, and are 
remarkable as containing in the Bavarian deposits the remains of the 
oldest-known bird, the Archwopteryx macrura. 
The Lower Oolites embrace the Inferior Oolite, the Great Oolite, 
and Cornbrash. The Stonefield Slate occurs at the base of the Great 
Oolite ; its fossil remains show that the life of the period greatly 
resembled that of Australia at the present daj’', where marsupials, 
sharks cycads, and pines still fiouri.sh. 
