OCR Text |
Show 716 MR. E. A. SMITH ON SHELLS FROM LAKE NYASSA. [Nov. 6, 10. LANISTES SOLIDUS, sp. nov. (Plate LXXIV. figs. 10, 11.) Shell thick, solid, imperforate when adult, globosely ovate, yellowish olive, with the faintest indication of spiral linear bands, smooth with the exception of roughish lines of growth and most minute (almost obsolete) spiral strise not visible to the naked eye ; whorls 4\, with a broad shallow depression or excavation above, then very convex ; last whorl large, ventricose, rapidly enlarging towards the aperture, the latter pyrit'ormly ovate, purplish, or golden and iridescent within, golden towards the lip and on the columella, which is thickened and reflexed over the umbilical fissure; operculum horn-colour, concave exteriorly, with the internal scar roughly corrugated. Length 42 millims. ; diam. of last whorl, above the aperture, 30. Length of aperture 30, diam. 20. Another specimen is 39 millims. long, 28 wide, and its aperture 30 in length and 18-J in width. L. nyassanus of Dohrn is very like the present species in some respects. In solidity, in the absence of an open umbilicus, and in texture it is similar. But the vast difference of form is of itself quite sufficient to separate the two varieties. Neither can L. solida be the young state of Dohrn's shell, because the specimens before me have all the appearance of being mature, being solid and very heavy for their size ; and on comparison with young examples of that species also obtained by Mr. Simons, the specific distinctness is at once observable. 11. LANISTES AFFINIS, sp. nov. (Plate LXXIV. fig. 7.) Shell ovate, thin, widely umbilicated, greenish olive, with a narrow yellow line winding around the top of the whorls at the suture, smooth, shining, sculptured with oblique lines of increase and most minute spiral strise, which are only visible under a lens ; whorls five, convex ; aperture ovately pyriform, purplish, and iridescent within, becoming yellow at the lips and columella, which is very slightly reflexed. Length 38 millims., diam. 27 \. Length of aperture 26, width 16|. This species may be known from L. solida by its more prolonged spire, which consists of half a whorl more than in that species, and by its open umbilicus, which gives the last whorl a very different form. L. ovum, Peters, is another closely allied form, and at first sight might easily be confused with this species. The latter has a shorter and less conical spire, consists of half a whorl less, and its body-whorl and aperture are longer. 12. PALUDINA JEFFREYSI, Frauenfeld. (Plate LXXIV. figs. 1,2.) Viviparajeffreysii, Frfld. P.Z.S. 1865, p. 659. This species was first found at Lake Nyassa by Dr. Kirk. The specimens collected by Mr. Simons do not quite accord with Frauen-feld's diagnosis. This author has omitted to mention that the en- |