ACLTS. 



219 



A. AscARis, Turton. 



Rather slenderly turreted, spirally ridged throughout : suture 

 oblique ; mouth oval : axis imperforate. 



Plate LXXXVIII. fig. 8. 



Turbo ascaris, Turt. Conch. Diction, p. 2] 7. 



Alvania supranitida, Searles Wood, Catal. Crag Moll, (teste S. W.) 



Turritella ascaris, Hanl. Brit. Marine Conch, p. xlv. f. 21 (magnified, worn). 



Pyramis acutissimus, Brown, Illust. Conch. G. B. p. 15, pi. 9, f. 36 ? 



AcUs supranitida, Loven, Index Moll. Scand. p. 17 (probably ; no description). 



So rare is this minute but elegant species that we have 

 never seen more than three or four specimens of it. It is 

 of a tapering and rather slender turreted shape, thin, and 

 of a pure uniform white ; its lustre and transparency we 

 cannot speak of, not having examined the shells of living 

 examples. It is spirally ridged, with rather square-topped 

 narrow regular and equidistant ribs, whose intervals are 

 smooth, and sometimes twice as broad as the raised sculp- 

 ture. These ridges, which seem to continue, though less 

 prominently so, to the base of the body, are five in number 

 upon the penult and antepenult turns. The uppermost 

 one is occasionally rather less distinct than the rest ; the 

 lowest one is very near the oblique sutural line, which, 

 owing to the roundness of the volutions (about eight in 

 number) and the profundity of their slant both above and 

 below, is very strongly pronounced, though not canali- 

 culated. The longitudinal increase of the volutions is 

 rather quick ; the body is attenuated below, its basal 

 declination is gradual and rounded. The mouth is of an 

 obliquely oval shape, and occupies about a fourth of the 

 entire length : it is about half as long again as it is broad ; 

 is somewhat rounded, and not wide at the anterior base, 

 and is chiefly prominent at the posterior extremity. The 



