MOLLUSCA FROM EQUATORIAL AFRICA. 195 



and rather coarser transverse sculpture ; the umbilicus is nar- 

 rower and the columella descends almost vertically in a very 

 slight curve and extends above into a thickish, well-defined, 

 parietal callus ; the aperture is also much more rectangular than 

 in that species. 



Alt. 9"5, diam. maj. 7, diam. min. 5*75 mm. 



Aperture : alt. 3*75, diam. 3 mm. 



Hah. Mt. Elgon, Uganda (C. W. Woodhouse). 



Streptaxis marsabitensis, sp. n. (PI. XXXII. figs. 2, 2 «.) 



Shell very depressedly turbinate, cream-coloured ; whorls 4|, 

 regularly increasing, the earlier whoi'ls smooth, polished, shining, 

 the later whorls sculptured with moderately fine, closely set, 

 arcuate riblets which become obsolete on the base of the shell ; 

 sutux'e impressed ; umbilicus wide, deep ; columella de.scending in 

 an oblique curve, white, slightly expanded, outwardly extending 

 above into a somewhat thick, well-defined, polished, parietal 

 callus which reaches the upper margin of the labrum ; labrum 

 white, considerably expanded -and reflexed below, slightly so 

 above, where it is gibbously bent somewhat downwards in front, 

 thus forming, with the parietal wall, a broad, but very shallow, 

 sinus ; aperture obliquely and broadly sublunate. 



Alt. 7, diam. maj. 13*75, diam. min. 11"25 mm. 



Aperture : alt. 5, diam. 4'5 mm. 



Hab. Northern slopes of Mt. Marsabit, British East Africa, at 

 an altitude of 4600 feet (^A. Blayney Percival). 



Streptaxis urguessensis, sp. n. (PI. XXXII. figs. 3, 3 a.) 



Shell allied to S. marsahitensis, bvit differing from that species 

 in its larger size, broader, but proportionately no higher, form, 

 and rather coarser transverse sculpture above, though the basal 

 sculpture, while being much more mai'ked, is considerably 

 finer; the umbilicus is proportionately slightly narrower and the 

 columella more obliquely descending; the labrum has converging 

 margins and is more sinuous and gibbously bent downwards over 

 the aperture, which is subrectangular and much broader in shape 

 than is the case with *S'. marsahitensis. 



Alt. 9'5, diam. maj. 16, diam. min. 13 mm. 



Aperture: alt. 7, diam. 5*5 mm. 



Hab. XJrguess, British East Afiica {A. Blayney Percival). 



Streptaxis desiderata, sp. n. (PI. XXXII. figs. 1, 1 a.) 



Shell suborbicular, very depressedly turbinate, polished, shining, 

 cream-coloured; whorls 5|, regularly increasing, the last some- 

 what rapidly broadening towards the apertui-e, marked only with 

 indistinct, transveise growth-ridges ; suture impressed, rather 

 coarsely crenellate ; umbilicus open, broad, deep; columella 

 descending in an oblique curve above, very oblique below, reflexed, 

 whitish, diffused into a thin, fairly well-defined, and broadly, 

 outwardly extending, parietal callus which reaches the vipper 



