OCR Text |
Show 1877.] MR. E. A. SMITH ON SHELLS FROM LAKE NYASSA. 717 tire surface is covered with faint spiral strise, which are distinctly visible to the naked eye. The very shallow depression around the middle of the body-whorl in the type specimen I am inclined to regard as an individual pecularity, and not a specific character; for there is no trace of such a furrow in any of the shells just received. 1 hese, for the most part, have the spire rather more elongated than the type, and the umbilicus a trifle narrower. 13. PALUDINA CAPILLATA, Frauenfeld. (Plate LXXIV. figs. Vivipara capillata, Frfld. P. Z. S. 1865, p. 659. Hab. Lake Nyassa (Dr. Kirk). 14. PALUDINA ROBERTSONI, Frauenfeld. (Plate LXXIV. figs. 5, 6.) Vivipara capillata, Frfld. I. c. Hab. Same as preceding species. 15. PALUDINA POLITA, Frauenfeld. Paludina polita, Frfld.; Reeve, Conch. Icon. xiv. sp. 73, fig. 73 ; Dohrn, P.Z.S. 1865, p. 233. Hab. South Africa (?). Lake Nyassa (Dr. Kirk). 16. BYTHINIA STANLEYI, sp. nov. (Plate LXXV. figs. 21, 22.) Shell small, ovate, rather solid, subrimate, dirty white or yellowish, obliquely striated by the lines of growth; whorls four, slowly increasing, very convex ; suture simple, rather deep ; mouth sub-circular, occupying about half the whole length of the shell; peristome stout, thickened. Length 5 millims., diam. 3L. Hab. Lake Nyassa. The solidity, very convex whorls, and subcircular aperture, are the chief distinguishing characteristics of this little shell. The operculum, of course, takes the form of the mouth, and has the lines of increment rather coarse near the margins. I dedicate this little shell to M r . Henry M . Stanley, as a mark of admiration of his undaunted perseverance and achievements in African exploration. 17. PHYSA NYASSANA, sp. nov. (Plate LXXV. figs. 16, 17.) Shell solid, pale olive-brown, narrowly perforate, somewhat triangular, roundly angulated above, and with a very short depressed spire; whorls five, convex, separated by a deep channelled suture, and sculptured by fine lines of growth; last whorl very large, occupying almost the entire length of the shell, since the spire is very shortly conical and only slightly elevated; aperture large, only a trifle shorter than the whorl, subauriform ; columella thickened and a little reflexed, subtortuous, and connected with the upper extremity of the outer lip by a thin callous deposit upon the whorl. P R O C . Z O O L . S o c - 1 8 7 7 , N o . XLVII. 47 |