RISSOA. 29 



of Rissoa which can be safely identified with his descrip- 

 tions or figures were placed by him in the genus Turbo. 



14. R. albel'la"*, Loven. 



E. crfbeUa, Lov. Ind. Moll. Scand. p. 25. R. inconspicua, var. tenuis, F. 

 & H. iii. p. 115, pi. lxxxiii. f. 7, 8. 



Body yellowish- white, with a purplish blotch in the middle : 

 pallial process single, issuing from the upper angle of the mouth 

 of the shell : snout rather short, deeply cloven lengthwise, not 

 extending as far as the foot : tentacles cylindrical, with blunt 

 tips, usually spotted with yellow or opaque-white, and finely 

 setose : eyes on very small tubercles : foot truncated (occasion- 

 ally somewhat bilobed) in front, constricted near the middle, 

 and pointed behind ; sole slightly grooved in the centre of the 

 posterior half: appendage single, leaf- like, flat and large. 



Shell conic-oval, thin, semitransparent, and glossy ; sculp- 

 ture, usually a few minute slight spiral striae, but sometimes 

 also rather sharp and curved longitudinal ribs, of which there 

 are from 12 to 15 on the penultimate whorl ; these ribs never 

 cover the uppermost whorls, nor extend to the mouth, and now 

 and then they appear on the middle whorls only ; between the 

 labial rib (which rarely occurs on smooth specimens) and the 

 outer lip there is a greater or less space left, so as sometimes 

 to give this rib the aspect of a varix : colour yellowish-white 

 of different shades, often variegated by longitudinal reddish- 

 brown or tawny streaks, which are straight and rather nume- 

 rous on the upper whorls, and more or less flexuous on the 

 body-whorl ; the base is occasionally marked with a broad but 

 indistinct tawny band ; some specimens are of a bright bronze 

 hue : spire varying in length, sharp-pointed : whorls 6-7, tu- 

 mid, gradually increasing in size ; the last occupies about 

 three-fifths of the spire : suture remarkably deep : mouth oval 

 or roundish-oval, not expanding: outer Up very thin, contracted 

 and incurved at the upper corner: inner lip somewhat thickened, 

 and reflected, especially over the base, where a small umbilical 

 crevice is formed : operculum slightly concave, horncolour, 

 with a short spire, and rather strongly striated. L. 0-15. B. 

 0-075. 



Var. Sarsii. Thinner, smooth, and seldom having the labial 

 rib. R. Sarsii, Lov. I. c. p. 15. 



* For albula. whitish. 



