RISSOA. 33 



16. R. viola'cea*, Desmarets. 



B. violacea, Desra. in Bull. sc. soc. phil. Paris, p. 8, pi. i. f. 7. JR. ri'.fi- 

 labrum, F. & H. iii. p. 10(3, pi. lxxvii. f. 8, 9. 



Body orange-white, striped in front with purplish-brown : 

 mantle not exhibiting any process : tentacles slender, setose, 

 marked lengthwise with an orange line : eyes conspicuous on 

 bulbs at the outer base of the tentacles: foot rounded and double- 

 edged in front ; sole constricted in the middle to such an ex- 

 tent that the front part of the foot appears to issue from the 

 hinder part, as if out of a sheath, and it is finely grooved 

 lengthwise towards the tail : appendage single, short, and 

 conical ; it proceeds from the hinder edge of that lobe of the 

 mantle which forms the operculum. 



Shell conic-oval inclining to oblong, solid, nearly opaque, 

 rather glossy : sculpture, usually strong, prominent, and slightly 

 curved longitudinal ribs, about 15 of which are on the penul- 

 timate whorl, those on the last whorl being present only on the 

 under side ; there are none on the upper whorls, which are 

 quite smooth ; near the mouth is a very large and broad labial 

 rib or callus ; the interstices of the ordinary ribs and the rib- 

 less part of the last whorl are covered with numerous rows of 

 fine transverse striae", which are regularly and closely punc- 

 tured : colour whitish, frequently tinged with yellow, reddish- 

 brown, violet, or purple ; some specimens are marked length- 

 wise by reddish-brown streaks, especially on the upper part ; 

 the tip is usually orange ; the outside edge of the labial rib is 

 mostly tawny, and the inside of the lip violet : spire short, 

 more or less abruptly tapering to a fine point : whorls 7, rather 

 tumid ; the last occupies nearly three-fifths of the spire, and 

 is somewhat compressed and dilated towards the mouth i suture 

 slight, overlapping the preceding whorl : mouth roundish-oval, 

 wide, and slightly expanding in every direction : outer lip thin : 

 inner lip broad, reflected on the pillar and towards the base : 

 operculum horncolour, thin, composed of three rapidly increas- 

 ing volutions, and marked with very fine and close flexuous 

 striee in the line of growth. L. 0-2. B. 0*1. 



Yar. 1. ecostata. Destitute of the ordinary ribs. 



V"ar. 2. porifera. Body yellowish and stained with dark- 

 purple on the upper side, whitish on the under side : mantle 



* Violet-coloured. 



c o 



