•286 MR. E. A. SMITH ON SHELLS FROM [Feb. 15, 



purplish dotted with brown, whitish at the suture and at the base. 

 Spire acutely conical, with rectilinear outlines. "Whorls 7, flat, 

 sloping, with a broad deep furrow at the lower part, which is 

 margined above by a keel, which on the upper volutions is simple, 

 remarkably prominent and acute, and giving to them quite a 

 pagoda-like appearance. On the last two and a half whorls it is 

 less acute and minutely nodulous ; and above that there are three 

 other granulous ridges, whereof the uppermost, or that immediately 

 beneath the suture, is conspicuously the largest ; these gradually 

 become finer and less granulous as they ascend the spire, so that 

 upon the first few whorls they are simple thread-like Urse ; the last 

 whorls also exhibit fine lirae of a similar character between the 

 larger granulous keels, and the entire surface is ornamented with 

 very fine hnes of growth. The body-whorl is sharply angulated 

 and carinate at the middle ; and the slightly convex base bears 

 about eight principal concentric ridges with iuterlying finer thread- 

 like ones. Aperture subquadrangular, within purplish at the upper 

 part and whitish beneath, equalling about -f^ of the entire length of 

 the shell. Outer lip thin, obliquely receding, a little incurved above 

 the carina, not thickened. Basal margin broadly sinuated, ex- 

 curved, and slightly effuse. Columella thin, arcuate, a trifle re- 

 flexed at the umbilicus, and joined to the upper extremity of the 

 labrum by a thin white callosity. Operculum horny brown, about 

 5-whorled, distinctly marked with arcuate lines of growth. 

 Length 18 millims., diam. II ; aperture 7i long, 6 broad. 



Hab. Lake Tanganyika {Thomson). 



I feel much pleasure in naming this species after Mr. Thomson, 

 its discoverer. Among the several forms new to science contained 

 in his collection this is perhaps the most remarkable. The colouf 

 of it is very difficult of description. The general tone of the spire 

 is a sort of livid purphsh tint, divided into zones by the whitish 

 furrow which encircles the whorls immediately above the suture. 

 The tubercles, too, upon the ridges also stand out in pale relief; 

 and the interstices between them are frequently dotted with brown. 

 The keel around the middle of the body-whorl is scarcely tuber- 

 culous, or at all events much less so than the carinse above. The 

 base is almost entirely white, with the exception of red dotting 

 sometimes present upon some of the larger ridges, which exhibit 

 hardly any indication of tubercles. The eff'use broad siuuation in 

 the base of the aperture is best seen when the base of the shell 

 confronts the eye. 



22. LiMNOTROCHus KiRKi. (Plate XXXIII. figs. 18-18 6.) 

 Limnotrochus Icirlcii, Smith, Ann. & Mag. N. H. 1880, vi. p. 426. 

 Shell solid, trochoid, dirty whitish, deeply and narrowly umbili- 

 cated. Spire acutely conical. Whorls 6 or 7, feebly concave, 

 bearing arcuate and flexuous lines of growth and six or seven granu- 

 lous lirse, whereof that immediately above the suture is the largest ; 

 body-whorl acutely angular at the periphery, encircled by two sub- 



