44 ZOOLOGICAL EESULTS OF THE EUWENZOEI EXPEDITION. 



irregulariter concentricis sculptus ; apertura obliqua, subquadrata, brevis ; peri- 

 stomium tenue, margine columellari ad insertionem breviter expanse et reflexo. 

 Alt. 8'5 mm., diam. 11. 



a. Mubuku Valley, E. Ruwenzori, 10,000-14,000 feet. 



Under a lens the plicse look quite rib-like ; they do not extend below upon the 

 keel so as to affect the regularity of it. 



T. mamboiensis Smith * is similar in form, but less strongly plicate upon the 

 upper surface, and the concentric sculpture upon the base of the body-whorl is more 

 distinct than in the present species. It is also darker in colour. 



3. Tkachycystis 1 ruwenzokiensis, sp. n. (Plate I. figs. 9-11.) 



Testa orbicularis, depressa, tenuis, anguste umbilicata, olivaceo-cornea, ad apicem 

 albida, vix nitida, lineis increment! arcuatis conspicuis subplicatis ornata ; spira 

 parum elata, ad apicem obtusa ; anfractus 5, sutura subprofunda sejuncti, con- 

 vexiusculi, regulariter accrescentes, superiores duo Iseves, ultimus baud de- 

 scendens, infra plicis vel striis minus conspicuis ; apertura oblique lunata ; peri- 

 stomium tenue, simplex, margine columellari ad insertionem dilatato et reflexo. 

 Diam. maj. 13 mm., min. 10^, alt. 6|. 

 a-d. Mubuku Valley, E. Euwenzori, 10,000-14,000 feet. 



In form this species is rather like Helix hukohce Martens f , but is more narroM'ly 

 umbilicated. The colour of the latter species, moreover, is described as chestnut-brown, 

 with a light zone on the body-whorl. 



The present species is so thin that the underside of the body-whorl is liable to 

 wrinkle when dry. The lines of growth are well-marked, even finely plicate above. 



4. Ena (Cerastus) eetirugis (Martens). 



Buliminus retirugis Martens, Deutsch-Ost-Afrika, vol. iv. p. 60, pi. iii. fig. 25. 



a. Euwenzori (no particular locality given). 



A single specimen agreeing in all respects with the description, excepting that the 

 network or malleation is of the same colour as the rest of the shell and not pale 

 yellow. It is rather smaller than the type, having a length of 24 mm. E. lagariensis 

 Smith is probably only a variety of this species in which the malleation is almost 

 obsolete, and Buliminus [Petroeus) aloysii sabaudice Pollonera is the same, or a 

 very closely allied form. 



5. AcHATiNA SCHWEINFURTHI, var. (Plate I. fig. 8.) 



Achatina schwewfurthi Martens ; Pilsbry, Manual Conch, vol. xvii. p. 61, pi. vi. fig. 15. 



a. Ruwenzori (no special locality stated). 



* Ann. Mag. Nat. Hist. 1890, vol. vi. p. 151, pi. v. fig. 3. 

 t Deutsch-Ost-Afrika, vol. iv. p. 58, ^\. iii. iig. 23. 



