285 



DESCEIPTION OF TWO NEW HELICOIDS FEOM BRITISH EAST 

 AFEICA AND UGANDA. 



Ey H. B. Preston, F.Z.S. 

 Read 13th December, 1912. 



GuDEELLA, n.gen. = Thapsiella, Gude, non Fischer. 



The name Thapsiella, used for the group of African zonitoid land 

 molluscs by Mr. G. K. Gude/ and which includes the two new species 

 described below, being apparently preoccupied by Fischer in 1884 

 for a section of Alvania, llisso, it becomes necessary to substitute 

 a new name for Mr. Gude's genus. I have, therefore, much pleasure 

 in proposing the name Gndeella in its stead. 



Genotype : Gndeella Mastihtensis, Smith, from Central Africa. 



GuDEELLA. KiGEZlENSIS, n.Sp. 



Shell rimate, depressedly suborbicular, moderately tliin, reddish 

 brown, polished, shining, base of shell spirally marked with lines of 

 yellowish grey ; whorls 4^, regularly increasing, smooth but for 

 transverse growth-markings; suture impressed, narrowly margined 

 below; umbilicus narrow, deep; columella obliquely descending. 



outwardly expanded above; labrum simple; aperture broadly and 

 compressedly sublimate. Alt. 3"75 mm. ; diam. maj. 7"75, min. 

 6-5 mm. Aperture: alt. 3"25, diam. 3'25 (nearly) mm. 



ITab. — Kigezi, extreme South- West Uganda, at an altitude of 

 6,000 feet (Robin Kemp). 



GuDEELLA Vernhout:, n.sp. 



Shell depressedly turbinate, polished, shining, yellowish brown ; 

 whorls 4^^, regularly increasing, sculptured throughout with very 

 fine and closely set silky spiral striae ; suture impressed, margined 

 below ; umbilicus narrow, deep ; columella very narrowly outwardly 



A 



expanded above, very obliquely descending, not curved ; labrum 

 simple; aperture obliquely crescentic. Alt. oSmin.; diam. maj. 6'25. 

 min. 5'25 mm. Aperture: alt. 2'75, diam. 2'75 mm. 



Ilab. — Urguess, Britisli East Africa (A. Blayney Percival). 



^ Proc. Malac. Soc. Lend., vol. ix, p. 27'2. 



