RISSOA. 113 



R. iNcoNSPicuA, Alder, 



Not particularly minute, ranging in shape from oblong-conic 

 to abbreviated ovate-conic ; either wholly white, or spotted or 

 longitudinally streaked with fulvous or rufous on a yellowish 

 white ground. Whorls decidedly convex, not perfectly smooth, 

 nor distinctly cancellated ; if not ribbed, yet always with traces 

 of longitudinal or spiral obsoletely projecting lines. Mouth 

 shorter than the spire, not edged with lilac or rufous, nor painted 

 externally with any arched line of colour (as in parva). Throat 

 smooth. A subumbilical crevice. 



Plate LXXVI. fig. 7, 8 ; LXXXII. fig. 5 to 9. 



? Tu7-bo albulus, Adams, Trans. Linn. Soc. vol. iii. pi. 13, f. 17, 18. — Maton 

 and Rack, Trans. Linn. Soc. vol. viii. p. 185. — Turt. 

 Conch. Diction, p. 230. 

 Bissoa inconspicua^ Alder, Annals Nat. Hist. vol. xiii. p. 323, pi. 8, f. 6, 7. 

 „ maculata. Brown, Illust. Conch. G. B. p. 12, pi. 9, f. 5, Cy. 9 

 „ similis. Brown, Illust. Conch. G. B. p. 13, pi. 8, f. 20, ? 



The Rissocc inconspicua is perhaps one of the most 

 variable of the genus, or rather is that British species of 

 which we possess the greatest modifications in form and 

 sculpture. Mr, Alder's original delineation of it combines 

 characters that are not often found together in such high 

 development ; hence, despite its correctness, few specimens 

 would be positively determined by comparison with it. 

 The shape ranges from abbreviated ovate-conic to oblong- 

 conic, but certain fixed conditions appear to accompany 

 the difference of figure ; the broader individuals being 

 ribbed, solid, and more or less marginated at the lip ; 

 whilst the more produced examples are thin, semi-trans- 

 parent, comparatively smooth, and have the margin of the 

 lip more or less acute. The surface is of a glossy white, 

 either uniform (as in the more solid and dead individuals) 

 or with a yellowish tinge, and occasionally painted with 



VOL. Ill, tt 



