98 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



The unusual number of the volutions and the sudden inflation of the last volution 

 renders its discrimination easy. 



The height is about equal to the transverse diameter of the last volution. 



Geological Position and Locality. Collected by E. Witchell, Esq., in the Great Oolite 

 of Bussage, near Bisley Common; it has also occurred rarely in the Cornbrash of 

 Scarborough. 



RISSOINA SUBULATA, Lye. Tab. XLI, fig. 9. 



Testa elongata, subcylindrica, anfractibws (9) convexis, altis, longitudinaliter oblique 

 costellatis, costellis, crebris (circa 30 in ambitu), apertura ovato-obliqua, parva. 



Shell .elongated, subcylindrical, volutions (9) convex, high, longitudinally obliquely 

 costellated, costellse closely arranged (about 80) in a volution; aperture ovate, oblique, 

 small. 



A slender, subulate, delicately ornamented shell ; the height of the volutions is equal to 

 three fourths of their opposite diameter. 



Geological Position and Locality. The Forest Marble of Laycock ; in the collection of 

 W. Walton, Esq. 



RISSOINA (?) TUMIDULA, Lye. Tab. XLIV, fig. 13. 



Testa ovato-tumidula leevigata, spira elevata, anfractibus (5) convexis, latis, suturis bene 

 distinctis, apertura ovata, antice angulata, labro externo crasso. 



Shell ovate, inflated, smooth; spire short, but elevated; volutions (5) convex, wide, 

 their sutures deeply impressed ; aperture ovate ; the outer lip thick, forming an angle at 

 its junction with the base of the columella. There is no distinct notch. 



A short, inflated species, resembling in the figure of the aperture R. laevis, Sow., both 

 seeming to constitute aberrant examples of Rissoina, and approximating to Rissoa. 



Geological PosUion and Locality. Collected by E. Witchell, Esq., in the Great 

 Oolite of Bussage, near to Bisley Common, Gloucestershire. 



NERITA CLAVATULA, Lye. Tab. XLV, fig. 3. 



Testa hemispherica, spira parva, subdepressa, anfractu ultimo per magno, inflate, tuber- 

 culis parvis, remotiusculis, per series quinis, regularibus, et lineis radiantibw, tenwibus, 

 decu#satis ; basi carina una, l&vigata. 



Shell hemispherical ; spire small, obtuse, and rather depressed ; the last volution very 



