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Show 288 MR. E. A/SMITH ON SHELLS FROM [Feb. 15, 25. LITHOGLYPHUS RUFOFILOSUS. (PlateXXXIII. figs.20, 20a.) Lithoglyphus rufofilosus, Smith, Ann. & Mag. N.H. 1880, vi. p. Shell globose, thick, rimate, white, encircled with very fine, thread-like red lines, covered with a very thin epidermis. Whorls 5|, rapidly increasing, convex, separated by a simple deepish suture, striated by the lines of growth ; last whorl large, globose. Aperture also iarge, inversely rather pyriform, whitish, occupying about l of the entire length of the shell. Peristome continuous. Outer lip thin ; base and columella thickened, the latter particularly so, and reflexed. Length 13 millims., greatest diameter 11^-; aperture 10^ long, 6 broad. Operculum dark brown, ovate, straighter on the inner or columellar side, paucispiral in the centre, which portion is surrounded by concentric layers. Hab. Lake Tanganyika {Thomson). The operculum of this species resembles that of Tiphobia in miniature. The centre of it is paucispiral or littorinoid; and this part is inclosed by a border which apparently consists of concentric layers. The number and distance apart of the thin red lines are subject to variation, one specimen having as many as twelve upon the body-whorl, and another as few as four. SYRNOLOPSIS. Syrnolopsis, Smith, Ann. & Mag. Nat. Hist. ser. 5, vol. vi. p. 426 (1880). Shell subulate, smooth, imperforate. Aperture broadly sinuated at the base, with the outer lip slightly thickened, widely sinuated in the middle, and produced towards the lower part, furnished far within with one or two prominent lirae. Columella thickened, with a distinct plait at the upper part, and joined to the upper extremity of the labrum by a thin callosity. Operculum unknown. This curious form has all the appearance of a marine genus, in fact closely resembling Obeliscus or Syrnola. The basal sinuation of the aperture is similar to that in some species of Rissoina; but the plication on the columella is wanting in that group. This is not very prominent in the adult shell; nor are the two lirae within the aperture visible, except through the semitransparent shell, unless the lip is broken away. On removing a portion of it these become apparent, the upper one being the thicker and extending parallel with the suture for about the distance of half a whorl, the lower one being shorter and more slender. The fold on the columella becomes remarkably prominent as it ascends the spire; and this may be observed by grinding off one side of the shell. As nothing is known of the animal, the systematic position of the genus is doubtful; however, it may temporarily be classed with the Rissoidae. 26. SYRNOLOPSIS LACUSTRIS. (Plate XXXIII. figs. 21-21 b.) Syrnolopsis lacustris, Smith, loc. cit. Shell smooth, glossy, elongate, subulate, imperforate, yellowish |