52 MOLLUSCA FROM THE GREAT OOLITE. 



Family LITTORINID.E. 



RISSOINA, D' Orbigny. 1842. 



Shell turrcted, acuminated; spire long, consisting of several whorls; aperture oval, 

 rather pointed at the two extremities ; outer lip thickened, emarginated ; columella 

 rounded, straight. 



RISSOINA DUPLICATA, Sow. Plate IX, fig. 10. 



RISSOA DUPLICATA, Sow. 1829. Min. Con., t. 609, fig. 4. 



Brown. Illust. Foss. Conch., t. 38, figs. 14, 15. 



Morris. Cat. Brit. Fossils, p. 161. 



Bronn. Index Palseont., p. 1092. 

 RISSOINA DUPLICATA, D'Orb. Prod. Paleont., p. 297. 



If Orb. Pal. Franc. Terr. Jurass., t. 237, figs. 1, 2. 



A. Testa parvd turritd, acutd ; anfractibus (6) in media angulatis; costulis longi- 

 tudinalibus anffustatis, remotiiisculis ; carind unicd in media anfractuum sitd; anfractu 

 ultimo, costulis numerosis longitudinalibm rectis ornafo, carind evanescence. 



Shell small, turreted, acute ; whorls (6) angulated, with remote, narrow, longitudinal 

 costse; each whorl has a low carina, situated a little beneath its middle part; the last 

 whorl has very numerous small, longitudinal and straight ribs ; the carina is scarcely dis- 

 cernible upon the last whorl. The costse upon the last whorl are twice as numerous as 

 upon the spire, and the figure of the whorl is nearly cylindrical, or slightly biangulated ; 

 and the carina becomes obsolete ; the JKissoa unicarina of Buvignier, and the Fusus cari- 

 natus of Roe'mer, approach very nearly to this species, with which they may possibly 

 be identical ; judging from the descriptions, however, there are certain points of distinction 

 which appear to separate them from our species. Length 2 lines. 



Locality. Ancliff and Minchinhampton Common ; at the latter place it is very rare, 

 and found only in the beds of planking. 



RISSOINA OBLIQUATA, Sow. Plate IX, fig. 19. 



RISSOA oBLiauATA, Sow. 1829 Min. Con., t. 609, fig. 3. 



Brown. Illust. Foss. Conch., p. 79, t. 38, figs. 19, 20. 

 Bronn. Index Palseont., p. 1093. 

 RISSOINA OBLIQUATA, D'Orb. Prod. Paleont., p. 297. 



R. Testa turritd, turbinatd, acutd; anfractibus (67) convexis et costatis ; costis a 

 dextro ad sinixlram obliquis. 



