— 57 — 



obliquely, while the aperture is much higher and proportionateh'' narrower 

 than is the case A%'ith P. laikipiaensis . 



Alt. 19.5, diam. maj. 10. diam. min. 9 mm. 



Aperture ; ait. 11.25, diam. 5.23mm. 



Hab. — Lake Naivasha, British East Africa (Robin Kemp). 



Physa masakaensis sp. n. — PL V, fig. 7. 



Shell moderateljr large, ovate, wath exserted spire, perforate, polished, 

 shining, somewhat thin, dark reddish-brown ; remaining whorls 3, shoulder- 

 ed above, marked with fine, transverse striae which become obsolète on the 

 lower portion of the last whorls; suture impressed, crenellated hy the 

 terminatonis of the transverse striae; umbilicus narrow, deep; columella 

 obliquely desceuding. rather broadly, outwardly expanded and difïused 

 above into an extremely thin callus which reaches the upper margin of the 

 labrum; labrum thin, acute, dilated below; aperture rather elongatety 

 ovate. 



Alt. 16.75, diam. maj. 11.25, diam. min. 9 mm. 



Aperture : ait. 11, diam. 5 mm. 



Hab. — Masaka, S.-W. Uganda (Robin Kemp). 



Physa mutandaensis sp. n. — PI. V, fig. 8. 



Shell ovate, rimate, moderately thin, slightly polished, reddish-brown, 

 ornamented with a broad, subsutural band of yellowish-brown ; whorls 4, 

 the first three regularly increasing, small, compressed, the last large, long, 

 slightly inflated, shouldered above, obsoletely plicate ; suture impressed, 

 margined below; umbilicus very narrow, almost concealed b}' the outward 

 expansion of the columella: columella descending vertically, rather 

 narrowly, outwardly expanded and diffused above into a thin, diaphanous, 

 pariétal callus which reaches the upper margin of the labrum; labrum 

 simple, acute; aperture elongately and narrowly, inversely auriform. 



Alt i-^, diam. maj. 8.75, diam. min, 7 mm. 



Aperture : ait. 8.75, diam. 4.25 mm. 



Hab. — Lake iMutanda, S.-W. Uganda (Robin Kemp). 



Physa rumrutiensis sp. n. 



Shell siniètral, irregularly ovate, perforate, thin, pale corneous; remain- 

 ing whorls 4, rather rapidly increasing, the last not very globose, marked 



