new Shells from British East Africa. 475 



Opeas avgustior^ sp. n. (Fig. 33.) 



Shell differing from 0. rumrutiensis in its rather narrower 

 form and more acuminate apex, in having an additional 

 whorl and a half, coarser transverse sculpture, crenellate and 

 not margined suture, more obliquely descending columella, 

 and shorter aperture. 



Alt. 7-25, diam. niaj. nearly 2 mm. 



Aperture : alt. 1'25, diam. "5 mm. 



Hah. Between Rumruti and Mount Kenia, British East 

 Africa. 



Opeas vicina, sp. n. (Fig. 31.) 



Shell differing from 0. angustior in its shorter and more 

 tapering form, ratjier more convex whoil>!, of which there are 

 but six, coarser sculpture, rather less oblique columella, and 

 shorter aperture. 



Alt. 5*25, diam. maj. 1'75, diam. min. 1'5 mm. 



Aperture : alt. 1, diam. "5 mm. 



Hab Between Rumruti and Mount Kenia, British East 

 Africa. 



Ancylus crassistriatics, sp. n. (Fig. 35.) 



Shell somewhat conical, oval, with subcentral apex, choco- 

 late-brown in colour, scu'ptured with coarse, wavy, radiate 

 stripe ; margin somewhat serrated ; interior reddish brown, 

 poli^iied, shining. 



Alt. 2, diam. maj. 4*5, diam. min. 3 mm. 



Hah. Between Rumruti and Mount Kenia, British East 

 Africa. 



Pisidium kenianum, sp. n. (Fig. 36.) 



Shell solid, somewhat trigonal, convex, very finely con- 

 centrically striate; umbones large; dorsal margin arched; 

 ventral margin rounded ; anterior side rather abruptly 

 descending; ])Osterior side slightly produced, rounded; 

 cardinal teeth in right valve small, oblique; anterior lateral 

 elongate, erect ; posterior lateral also elongate, slightly 

 rounded; cardinal teeth in left valve situated at an obtuse 

 angle to one another, the anterior broad below, the posterior 

 small ; the anterior lateral in left valve posteriorly bifid, 

 angled in the middle, outwardly projecting; the posterior 

 lateral elongately anteriorly bifid, also projecting, slightly 

 grooved above. 



