350 MR. E. A. SMITH ON SHELLS [Apr. 20, 



certainly flatter. Tlie largest of the Tanganyikan specimens exceeds 

 the dimensions given by Martens, and consists of 5^ whorls. Its 

 greatest diameter is 18 millims., smallest 15 ; and the aperture is 

 5 broad and 5 high. Smaller examples are precisely of the same size 

 as the original type. The colour of the freshest specimens is light 

 horny brown above, and paler on the undersurface. 



12. LiTHOGLYPHus zoNATus, Woodward, Proc. Zool. Soc. 1859, 

 p. 349, pi. 47. f. 3-3c. 



In both the specimens sent by Mr. Hore the umbilical callosity 

 completely conceals the rimation. The lip and the edge of the basal 

 excavation are remarkably acute. The whorls are four and a half in 

 number, rapidly enlarging, and convex. 



13. Pleiodon spekei. Woodward, Proc. Zool. Soc. 1859, 

 p. 348, pi. 47. f. 2; Conehologia Iconica, vol. xvi. f. 2; Kiister's 

 Con. Cab. (Iridina), pi. 70. f. 1. 



Two odd valves only of this fine species are in the collection sent 

 by Mr. Hore. The larger is of greater length than the specimen 

 described by Woodward, being nearly :)^ inches long and 2| broad ; 

 and the internal nacre is of the same salmon-colour. On the contrary, 

 the second valve is pearly white within, proportionally broader, less 

 sinuated at the basal margin, with the umbo more remote from the 

 anterior extremity, the muscular scars less deep, and the pallial line 

 further within the valve. 



14. Mutela exotica, Lamarck. 



Iridina exotica, Lamarck, An. s. Vert. ed. 2, vol. vi. p. 571 ; 

 Reeve's Conch. Icon. f. 2. 



I. nilotica, Sowerby, Zool. Journ. vol. v. pi. 2 ; Conch. Icon. f. 4 ; 

 Kiister, Con. Cab. pL 25. f. 3. 



This is the first record of this species from so southern a locality. 

 Only a single valve, about three inches in length, was obtained. 



15. Spatha tanganyicensis. (Plate XXXI. figs. 8, 8«.) 



Shell transverse, irregularly elliptic, somewhat winged, very in- 

 equilateral, gaping considerably anteriorly, and slightly at the oppo- 

 site extremity, concentrically sulcate ; hinge-line rectilinear ; ante- 

 rior end regularly curved, commencing at right angles to the straight 

 dorsal margin, and gradually curving obliquely into the base or 

 lower margin ; posterior end rather acuminately produced. The 

 acumination is sharply rounded, and formed by the upward sweep of 

 the ventral curve and the upper lateral slope, which is obliquely 

 subrectilinear, and joins the dorsal line at an angle of about 65 

 degrees. Epidermis brownish-olive, marked with very fine radiating 

 and close-set dark greenish-olive lines. Hinge with a single thin 

 lamellar tooth in each valve, extending from the umbo nearly as far 

 as and almost in a line with the dorsal margin. Anterior scar large, 

 irregular, indistinctly bipartite ; posterior one also large, transverse. 

 Beneath the hinge-line, a little posterior to the umbones, are two or 



