BIVALVIA. 63 
Geological Positions and Localities. This well-marked little Corbula has been kindly 
forwarded by J. F. Whiteaves, Esq., from the Great Oolite of Kirklington, Oxon. ; also by 
W. Walton, Esq., from the Forest Marble of Laycock, Wilts. 
CorsBuLa InvotuTa, Munst. Tab. XXXVII, figs. 4, 4a, 
CorBuLA INvoLuTA, Goldf. Pet., t. 151, fig. 14. 
CYPRINA — D’Orb. Prodrome, i, p. 278, No. 309. 
Testa crassa, parva, perinflata ; concentrice subtillissime striata ; umbonibus magnis 
obtusis, submedianis ; latere antico rotundo, postico rostrato, obtuse carinato et attenuato. 
Shell small, thick, greatly inflated, with very delicate, concentric striations; umbones 
large, obtuse, submesial ; anterior side short, rounded, posterior side attenuated, rostrated, 
its margin concave, and forming at its ower extremity an acute angle; the posterior slope 
has delicate, transverse striations; it is somewhat flattened, very narrow, and is only 
obscurely separated from the dorsal portion of the shell by an obtuse angle; the lower 
border is nearly straight. 
Length, one third greater than the height and the diameter through both the valves. 
The foregoing description will serve to distinguish it from a small, thick, but less in- 
flated species, abundant in the Great Oolite of Minchinhampton, and which was formerly 
regarded by me as C. cnvoluto of Munster, and figured under that title in Part II, Tab. VI, 
of the ‘Great Oolite Monograph,’ and described in Part II, p.97; it had previously 
been figured and described by Professor Buckman, in Sir R. Murchison’s ‘Geology of 
Cheltenham,’ 2nd ed., p. 97, pl. 3, fig. 4, under the title of Cordula striata ; but as that 
name had already been appropriated by Lamarck for an Hocene Corbula, it becomes 
necessary to change it to C. Buckmani, under which name it is refigured, Tab. XX XVII, 
fig. 8, thrice magnified. 
Geological Position and Locality. The Great Oolite of Karklington, Oxon. ; collected 
by J. F. Whiteaves, Esq. 
Corsuxa Isuirensis, Lyc. Tab. XXXVI, fig. 7. 
Testa parva, inflata, umbonibus medianis, magnis, erectis, latere anteriore rotundo, 
posteriore brevi, abrupte truncato, angulo obliquo instructo ; valvis longitudinaliter striatis, 
stris magnis regularibus, lineis angustis separatis ; lunula excavata ; basi subrecto. 
Shell small, inflated, but subquadrate or cuculeform ; umbones large, mesial, erect ; 
anterior side rounded, its lunule excavated ; posterior side short, abruptly truncated, with 
an oblique and subacute angle separating a posterior smooth and slightly concave 
area; the lower border is nearly straight; the dorsal surface has large, regular, 
