326 SECONDARY FORMATIONS. [Ch. XXIII. 
3. Oolite, or Jura limestone formation. 
This division, in which we do not include the lias, contains a 
great number of subordinate members, several of which may 
relate, perhaps, to periods as important as our subdivisions of 
the great tertiary epoch. The shells, even of the uppermost 
part of the series, appear to differ entirely from the species 
found in the division No. 1. 
4. The Lias. 
The shells of the argillaceous limestone, termed lias, and 
other associated strata, differ considerably from those of the 
preceding group, as do the greater number of species of ver- 
tebrated animals. 
5. Strata intervening between the Lias and the Carboniferous 
group. 
The formations which are referable to the interval which 
separated the great coal formations from the division last men- 
tioned, are very various, and some of them, like the new re 
sandstone, contain few organic remains. One group., however 
belonging to this period, the Muschelkalk of the Germans, 
which has no precise equivalent among the English strata, con 
tains many organic remains belonging to species perfectl 
distinct from the fossils of the lias, and equally so from thos 
of the carboniferous era next to be mentioned. 
6, Carboniferous group, comprising the coal-measures, the 
mountain limestone, the old red sandstone, the transitio 
limestone, the coarse slates and slaty sandstones called gray 
waclce by some writers, and other associated rocks. 
The mountain and transition limestones of the English geolo- 
gists contain many of the same species of shells in common 
and we shall therefore refer them for the present to the sam 
