'21 
MODIOLA imbricata. 
TAB, GCXII . — Figs, i and 3* 
Spec. Char. Oval, elongated ; with imbricated 
ridges upon the surface ; back angular, front 
concave. 
This is a slightly compressed shell ; about twice as long 
as broad ; the ridges upon the surface are the edges of 
the shell left prominent after each successive addition to 
its margin during its growth. The anterior lobe forms a 
slightly elevated ridge extending to the beak. 
The Rev. T. O. Marsh sent me the specimen (fig. 1) 
from Felmarsham, near Bedford. I have had larger 
casts brought me from Milton Ernest, also in Bedford- 
shire, by Mr, Goodhall, who has kindly favoured me 
with several shells obtained by him in the course of a 
short tour. Fig. 3 is from a much compressed and bro- 
ken shell, taken out of clayey Limestone, found in an 
alluvial deposit in the parish of Gisleham, near Lowes- 
toff, in Suffolk, by the friendly Mr. ThurtelL 
MODIOLA Hillana. * 
TAB. CCXII. — Fig. 2 . 
Spec. Char. Depressed, elongato-ovate, concen- 
trically striated ; posterior end narrow ; front 
slightly concave ; posterior lobe obscure. 
An elegantly formed shell, rather more than twice as 
long as wide ; the back forms a kind of keel from the 
centre of which the shell tapers towards the beaks ; these 
are not very prominent ; and together with the small 
