196 
ELEMENTS OE GEOLOGY. 
Fig. 122 . the-lSTaze, in Essex, we seem to have an ex¬ 
hibition of the oldest phase of the Red Crag ; 
and a warmer climate seems indicated, not 
only by the absence of many northern forms, 
but also by the abundance of some now liv¬ 
ing in the British seas and the Mediterranean. 
Voluta Lamherti (see Figs. 123 and 124), an 
extinct form, which seems to have flourished 
chiefly in the antecedent Coralline Crag pe> 
riod, is still represented here by individuals 
of every age. 
The reversed whelk (Fig. 125) is com¬ 
mon at Walton, where the dextral form of 
that shell is unknown. Here also we find 
most frequently specimens of lamellibranchiate molluscs, 
with both the valves united, showing that they belonged 
to this sea of the Upper Crag, and were not washed in 
from an older bed, such as the Coralline, in which case the 
Purpura tetragona, 
Sow.; nat. size. 
Fig. 123. 
Voluta Lamberti^ Sow. Va- Voluta Lamherti, young Trophon antiquum, Miill. 
riety characteristic of Suf- individual, Cor. and (Fu8usco7itrarius)hdL\f 
folk Crag. Pliocene. Red Crag. nat. size. 
ligament would not have held together the valves in strata 
so often showing signs of the boisterous action of the waves. 
No less than forty species of lamellibranchiate molluscs, with 
double valves, have been collected by Mr. Bell from the vari¬ 
ous localities of the Red Crag. 
At and near the base of the Red Crag is a loose bed of 
