— 327 — 

 Planorbis kisumiensis, sp. n. — PI. XVII, fig. lo. 



Shell sraall, suborbicular, depressed with concave spire, reddish brown ; 

 whorls 3, scLilptured with verj^ oblique, arcuate, transverse growth striae and 

 microscopic, pimctate, spiral striae; suture rather deeph' impressed; umbi- 

 licus ver)' wide, shallow; labrum acute, greath' receding below, projecting 

 in front, the marginsomewhat converging; aperturecompressedlysublunate. 



Alt. 1.25, diam. maj. 3.25, diam. min. 2.75 mm. 



Hab. — Kisumi, Lake Victoria Nyanza, British East Africa 

 (Robin Kemp). 



Physa permembranacea, sp. n. — PI. XVII, fig. 8. 



Shell perforate, ovate, very thin, shining, reddish brown; whorls 4, 

 rapidh' increasing, the last large, moderately inflated, marked with vertical, 

 transverse growth Unes crossed by microscopic, closely set, spiral, scratch- 

 like striae; suture impressed; columella descendiug in a curve, outwardly 

 expanded over the narrow umbilicus and diftused above into athin, red, well 

 defined, pariétal callus which reaches the margin of the labrum; umbilicus 

 narrow; labrum thin, erect, membranaceous; aperture large, broadh' inver- 

 sely auriform. 



Alt. 9, diam, maj. 5.5, diam. min. 4.75 mm. 



Aperture : ait. 6, diam. 3 mm. 



Hab. Abedare Range, Britisii East Africa (Robin Kemp). 



The e.Ktremely thin membranaceous texture of the shell is the 

 chief character of the species, in manv examples when the animal 

 is removed, so thin is the test, that it can be pressed inwards and 

 dented at will. 



Sphaerium congener, sp. n. — PI. XVII, 2. 



Shell closely allied to -S. vidoriœ Smith ('), but differing from that species 

 in its lighter colour, considerably coarser concentric striae and more com- 

 pressed sides 



Long. 6.5, lat. 8 mm. 



Hab. — Between Entebbe and Mbarara, S. W. Uganda (Robin 

 Kemp). 



(■) Proc. Zoat. Soc, ic,o6, p. 186, pi. X, fig. 16. 



