GASTEROPODA. 53 



Shell turreted, turbinated, acute ; whorls (6 7) convex and costated ; costse oblique, 

 directed from right to left. 



The costse are rather more elevated than in R. acuta, and the entire figure is more 

 turbiniform, the whorls being much more convex. Length from 2^ to 3 lines. 



Locality. Ancliff ; also very rarely at Minchinhainpton Common, in the planking. 



RISSOINA ACUTA, Sow. Plate IX, fig. 9. 



RISSOA ACUTA, Sow. 1829. Min. Con., t. 609, fig. 2. 



Brown. Illust. Foss. Conch., p. 79, t. 38, figs. 25, 26. 



Bronn. Index Palseont., p. 1090. 

 RISSOINA ACUTA, D' Orb. Prod. Pal&mt, p. 297. 



It. Testa pared, turritd, acutd; anfractibus convexiusculis 6, costulis angustatis subre- 

 motis longitudinalibus ; aperturd ovatd; labio dextro expanso. 



Shell small, turreted, acute ; whorls (6) slightly convex, with narrow, rather remote, 

 longitudinal ribs ; aperture oval ; right lip expanded. 



The surface is nearly smooth ; the longitudinal ribs, or rather lines, scarcely affecting 

 the evenness of the surface ; it is the most slender example of the genus which the Great 

 Oolite has produced. Length, 3 lines. 



Locality. Ancliff; and very rarely Minchinhampton Common, in the planking. 



RISSOINA CANCELLATA. Plate IX, figs. 12, 120. 



JR. Testa turbinatd, turritd, acutd; anfractibus convexis (8), angustis, transverse costatis; 

 coslis (6 7) intequalibus, lineis lonyitudinalibus decussatis ; aperturd laid. 



Shell turreted, turbinated, acute ; whorls convex (8), narrow, transversely costated ; 

 costae (6 7) unequal, decussated by longitudinal lines ; aperture wide. 



The upper costae of each whorl are smaller and more approximated than the lower ; the 

 convexity of the whorls is chiefly upon their lower portions ; the fine longitudinal lines 

 crossing the narrow encircling costae give to the surface a cancellated aspect ; the aperture 

 is acute above, rounded beneath. 



Locality. The soft Oolite beneath the planking of Minchinhampton Common furnished 

 this pretty little shell, of which we have not seen another example. 



RISSOINA TRICARINATA. Plate IX, fig. 13. 



R. Testa parvd, turbinatd, acutd; anfractibus convexis ; tricarinatis ; carinis crenulatis; 

 carind superiore apud suiuram positd; aliis in media et approximates ; anfractu ultimo ad 

 basem lineis tenuissimis notato; aperturd parvd, suborbiculari. 



8 



