64 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



longitudinal striations, separated by elevated, narrow lines, which disappear at the posterior 



angle. 



The height, length, and diameter through the united valves are nearly equal; the test 

 is thick. 



The shortness of the posterior side, its angle, and the greater prominence of the 

 umbones, will distinguish it from C. striata, Buck. [C. Buchnanii, nobis, PL XXXVII, 

 fig. 8). Corbula involuta, Munster, has the posterior side more lengthened and 

 rostrated, and is almost destitute of the posterior angle ; the striations upon the surface 

 are much more delicate and faintly traced, they are oblique rather than concentric or 

 longitudinal. Corbula cuculaformis, Kock and Dunker, is also allied to it, but with the 

 figure less inflated and with more pointed umbones ; it is therefore, probably, distinct. 

 Possibly C. amata, D'Orb., may be identical with our species, but unfortunately the few 

 words of description in the ' Prodrome ' of that author are insufficient to characterise it ; the 

 same remark will also apply to his C. Aglaya and C. Alimena. 



Geological Position and Locality. The Bradfordian beds of Islip, Oxon. ; collected by 

 J. P. Whiteaves, Esq. 



Corbula Hulliana, Mor. Tab. XXXVII, fig. 5. 



Corbula Hulliana, Morris. Hull. Mem. Geol. Surv., Cheltenham, 1857, pi. l.fig. 6. 



Testa crassiuscula, injlata, ovato-trigona, subaquivalvi, subcequilaterali, antice producta, 

 rotunda, postice attemiata, sulco obliquo et carina marginali obtuse; umbonibus magnis 

 subacutis incurvis ; basi subarcuato aut subrecto ; lateribus costis obliquis angustis, elevatis, 

 regularibus postice undulatis ; striis radiantibus decussatis. 



Shell of moderate thickness, much inflated, ovately trigonal, subsequivalve, subsequi- 

 lateral; umbones large, incurved, and pointed ; anterior side produced and rounded, posterior 

 side more attenuated, with an oblique groove and submargiiial, obtuse, rugose keel, the 

 base arcuated, or in other specimens nearly straight and slightly irregular ; the surface of 

 the valves with prominent, oblique, regular, narrow costa?, which are slightly undulated 

 posteriorly ; occasionally the left valve exhibits towards the middle of its lower portion a 

 few perpendicular striations, which decussate the costae and render the lower margin 

 dentated. 



The largest of the British Oolitic Corbulae, with the hinge -characters strongly marked; 

 the valves are less thick than usually obtains in the genus ; it is also apparently equivalve ; 

 a well-preserved specimen of the left valve is destitute of the perpendicular striations. 



Geological Position and Localities. The specimen figured in the ' Memoirs of the 

 Geological Survey of Great Britain' was obtained in thePorest Marble near to Northleach ; 

 it occurs in the same position at Hinton, at Parleigh, and at Kidlington, Oxon., specimens 



