1881.] Molluscao/Me Indo-Malayan Fauna, 1G3 



Rtssoina weinkauffiana, n. sp. 



Lanceolately and turretly produced, o£ a brownish white colour, spire 

 acuminate, with the apex minutely mammillate, composed of 2.} nucleolar 

 whorls, which are perfectly smooth and of a milky white colour ; whorls 

 9| (except the first 2|) longitudinally, evenly ribbed, ribs close -set, slight- 

 ly flexuous, a little more numerous and less developed on the last whorl, 

 which under the lens shows two spiral, subobsolete stria?, the upper one 

 of which starts from the top of the peristome, otherwise there is no spiral 

 sculpture, no groove at base but girt with a very thick callous rib, appa- 

 rently smooth, but under a powerful lens very minutely striate with a 

 slight " beading" at the top ; aperture polished, shining, thickened, broad- 

 ly emarginate at columellar base, peristome evenly rounded, with a thick 

 callosity behind it. 



Long. 6f, diam. 2\ mil. 



I only know of one closely allied species, a smaller form, JR. funicu- 

 lata, Souverbie, 1865, from New Caledonia, this species is also found at 

 the Andamans ; I have named this well marked form in honour of Dr. H. C. 

 Weinkauff of Kreuznach, who is now editing a Monograph of the genus 

 for the new edition of the Conchylien-Cabinet ; I found the species alive 

 under stones at Port Blair, at extreme low water ; it was tolerably abun- 

 dant. 



Rissoina keyilliana, Weinkauff. 



Conch.-Cab. II, 1881, Kowloon. 



Shell large, very thick and solid, lanceolately produced ; apical whorls 

 wanting, 1\ remaining, regularly pyramidally turreted, the last one rela- 

 tively very little larger or more tumid than the penultimate, the upper 

 three whorls regularly, and evenly longitudinally ribbed, ribs thick, close- 

 set, slightly flexuous, the last four whorls with similar, but thicker, less 

 flexuous and more unequal ribs, each of the last two having also, in a 

 line with the outer lip, two of these ribs united forming very broad and 

 thickened varices, the last whorl but two has a similar but less prominent 

 one, out of the line of the others and quite at the back of the shell, the 

 whorl above it again has a similar but more developed varex in front, almost 

 in a line with the columella ; throughout, under the lens, regularly and 

 very finely tranversely striated, at the base of the last whorl the ribs 

 become obsolete and the transverse striae incised and well developed sulca- 

 tions, on the upper portion of the same whorl the longitudinal ribs are 

 distinctly and characteristically, though somewhat obsoletely, biangulate ; 

 aperture shallow and small, not everted, within polished and shining, with 

 two or three denticulations, not canaliculate ; columellar margin nearly 

 upright, slightly twisted, a trifle bent back and rounded at base, outer lip 



