432 
LOWER OOLITIC ROCKS OF ENGLAND : 
the evidence of general lithological divisions. It is however both 
convenient and necessary to abide by the stratigraphical divisions 
in our descriptions of the several formations. 
Organic Remains. 
Although fossils, as a rule, are plentiful in the Cornbrash, there 
is no great variety in the remains preserved. Saurians and 
Fishes are rare. Cephalopoda are represented by few species : 
and of these Belemnites are exceedingly rare. Of other Mollusca, 
not many Gasteropods are to be found, but the Lamellibranchs, 
and especially species of Avicula, Gresslt/a, Homomya, Isocardia, 
Modiola, Myacites, Ostrea, Pecten, and Pholadomya are abun- 
dant, though the shelly matter is in most cases but poorly pre- 
served, and the specimens are often in the form of casts. 
Brachiopoda are exceedingly common, and Echinodermata are 
abundant. Other forms such as Polyzoa, Crustacea, and Corals 
are rare. No species of Plants are recorded, although lignite is 
found here and there. 
CORNBRASH FOSSILS. 
FIG. 118. 
FIG. 119. 
FIG. 118. Ammonites macrocephalus, Schloth. 
119. Ammonites discus, Sow. \. 
,, 120. Myacites securiformis, Phil. f. 
,, 121. Grossly a peregrina, Phil f. 
