BIVALVIA. 79 
ASTARTE FLExICosTATA, Lyc. ‘Tab. XL, fig. 26. 
Testa transversa, subtrigona, convexa, umbonibus anticis acutis, elevatis, margine an- 
teriore truncata, abrupte declivi inferne angula formante ; lunula magna levigata concava, 
margine acuto; margine inferiore subrecto ; margine posteriore imprimis subhorizontali 
postice oblique declivi ; superficie striis concentricis regularibus instructis, in medio evanes- 
centibus. 
Shell transverse, subtrigonal, convex; umbones anterior, pointed, and conspicuous ; 
anterior side truncated, descending abruptly, and forming an angle with the lower border 
at its extremity ; the lunule is large, concave, smooth, with an acute margin; the lower 
border is nearly straight ; the posterior margin is nearly horizontal for the half of its length, 
then slopes obliquely downwards ; the shell is moderately convex, with an oblique, obtuse 
angle, posterior to which the surface is more flattened; it has regular striations, which 
follow the direction of the lines of growth; they are conspicuous near to the umbones, 
but disappear upon the middle portion of the dorsal surface. 
Height, 5 lines; length, 7 lines; diameter through the united valves, 33 lines. 
Geological Position and Locality. Collected by E, Witchell, Esq., in the white stone 
(Great Oolite) of Bussage, near to Bisley Common ; a single specimen. 
GRESSLYA PEREGRINA, Phil., sp. Tab. XXXVI, figs. 2, 2 a, 4. 
In addition to the specimen figured in Pl. XV, Part IT of the ‘ Great Oolite Monograph,’ 
it has been deemed advisable to exemplify three other variations of form, by the aid of 
which the intermediate connecting links may readily be imagined. ‘This Gresslya is very 
abundant in the Cornbrash, both in Wiltshire and Yorkshire, so that ample opportunities 
are afforded of studying every variation of form which it presents; these, as will be seen 
from our figures, are so considerable and so common that it seems impossible fairly to 
disconnect from them some other examples of Gresslya from the Inferior Oolite, as Unio 
abductus, Phil., Gresslya latior, Ag., G. conformis, Ag., G. lunulata, Ag., G. erycina, Ag., 
G. concentrica, Ag., and perhaps also G. zonata, Ag. In all these the same kind of 
surface obtains, and the outer, granulated tegument is precisely identical, belonging to 
that section of the genus in which the radiating lines and the granules are of the most 
minute size, and very densely arranged. It has been usual to select for G. abducta 
Inferior Oolite examples with short forms, elevated umbones, tumid anterior sides, and 
compressed posterior sides; but the shortness of figure is surpassed by some from the 
Cornbrash, and the inflation of the anterior side varies in amount with every specimen. 
From these, probably, must be separated G. Jatirostris, Ag., which attains to large 
