60 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 
wards; lunule large, excavated; hinge-border curved and sloping downwards; the extremities 
are rounded and the base curves elliptically ; the concentric cost are regular, narrow, ele- 
vated, the interstitial spaces having delicate longitudinal striations. The convexity is mo- 
derate beneath the umbones, the extremities of the shell being rather compressed ; the 
general figure approaches to C. Leymerii, Buv., but that species has the posterior side 
shorter and less rounded. ‘The present shell is more lengthened than is usual with the 
Jurassic species, and the concentric costz are less conspicuous. 
Length, 19 lines; height, 12 lines; diameter through the valves, 9 lines. 
Geological Position and Locality. The upper portion of the Great Oolite, near 
Minchinhampton, in pale, buff-coloured Oolite; few specimens have been obtained, and 
these, for the most part, are only casts. 
Corsis ELLIPTICA, Whiteaves, MSS. Tab. XXXV, fig. 1. 
Testa ovato-elongata, depressa, umbonibus parvis medianis, margine antico subhorizon- 
tali, postico oblique declivi ; basi elliptico curvato ; superficie rugis longitudinalibus regu- 
laribus, magnis, elevatis, crebris. 
Shell ovately elongated, rather depressed; umbones small, but little elevated, mesial ; 
anterior margin nearly horizontal; posterior margin sloping obliquely downwards ; the two 
extremities of the shell are rounded, and the base is curved elliptically ; the surface is orna- 
mented with large, elevated, longitudinal, regular, and closely arranged rugz. 
Length, 73 lines ; height, half the length. 
A small, depressed, and unusually lengthened Corbis, which will not readily be mis- 
taken for any other known Jurassic species. 
Geological Position and Locality. The Forest Marble of Kidlington, Oxon., collected 
by Mr. Whiteaves. 
Corsis rotunDA, Walton, MSS. Tab. XL, fig. 17. 
Testa crassa, ovato rotundata, umbonibus magnis mediantis antrorsum curvatis, lateribus 
sub-equalibus postice subcompressa, superficie rugis concentricis magnis, crebris, sub- 
aqualibus ; etate adulto rugis obsoletis ; cardo dente antico lateral magno. 
Shell thick, ovately orbicular, subglobose ; umbones large, mesial, curved forwards ; the 
sides nearly equal, but the posterior side is slightly compressed and shortened ; the surface 
with large, closely arranged, concentric, but somewhat unequal rugz, which degenerate in 
the adult state and nearly disappear. 
It has sometimes been mistaken for Sphara Madridi, but it is more orbicular, and the 
