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Show 1877.J MR. E. A. SMITH ON SHELLS FROM LAKE NYASSA. 713 are fine, and about eighteen on a whorl, those on the penultimate volution bearing about eight nodules. 2. MELANIA TURRITISPIRA. (Plate LXXV. figs. 14, 15.) Shell small, turreted, ovately fusiform, pale olive ; whorls seven or eight, flat, with a raised infrasutural belt, furnished with coarse ribs, and sculptured with a few spiral striae, nearly obsolete on the upper whorls, except the one which marks off the raised band at the suture ; on the body-whorl the ribs become obsolete at the middle, where it is angulated, and the transverse striae are about eight in number ; the three or four upper ones crossing the costse give them a somewhat nodose appearance ; aperture small, subovate, acuminate above. Length 8 millims., diam. 3\. Aperture 3 long. This curiously short stunted-looking species is remarkable for its peculiar form, the turreted spire, and the strongly developed nodulous upper extremities of the longitudinal ribs forming an infrasutural belt. Certain varieties of M. polymorpha approach the present species in the style of sculpture; but the very different form of the latter and the absence of spotting easily distinguish it. The specimens now described may not be full-grown ; but it is to be presumed that larger examples would still exhibit the same short stunted form. 3. MELANIA PUPIFORMIS. (Plate LXXV. fig. 13.) Shell cylindrical, subpupiform, covered by a greyish epidermis ; whorls nine, flattish, constricted just beneath a raised belt at the suture, somewhat turreted, separated by a deep suture, furnished with coarse flexuous ribs, which are nodulous at the upper extremities through being crossed or intersected by a spiral furrow a little beneath the suture ; below this there are faint indications of one or two other transverse striae, giving the ribs a subnodose appearance. O n the body-volution the ribs are almost obsolete ; but around the middle two or three spiral sulci are more distinct than those on the upper portion of it Aperture small, acutely ovate, occupying less than one third of the whole length of the shell. Length 11 millims., diam. 3^. Aperture 3£ long. The cylindrical pupoid form of this little species is very remarkable. The last three whorls are of about the same diameter; and above these the spire rapidly diminishes, forming a short cone at the apex. The ribbing is very strong for so small a shell. Only two examples of this species have come under m y observation ; but M r . Simons informs m e that he has seen several others, and among them some which were larger than that now described. 4. MELANIA SIMONSI. (Plate LXXV. fig. 3.) Shell acutely pyramidal, thinnish, whitish spotted with red; whorls 9-10, divided by a deep, slightly oblique suture, but little convex, furnished with obliquely arcuate granulous ribs, which num- |