194 MR. H. B. PRESTON ON AGNATHOUS 



15. Diagnoses of New Species and Varieties of Agnatlious 

 Mollusca from Equatorial Africa. By H. B. Preston, 

 F.Z.S. 



[Received November 8, 1912 : Read February 18, 1913.] 



(Plates XXXII.-XXXY.*) 



Index. Pagg 



Geographical 194 



Systematic : 



Streptaxis: 5 new species 194^195 



Ennea : 53 new species ; 1 1 new varieties 196-216 



JEnnea si/ngenes, nom, nov. tor JS. consobrina... 216 



The species of which descriptions are given in the present 

 paper were chietly collected in East and East Central Africa by 

 Messrs. Robin Kemp, A. Blayney Percival, and C. W. Woodhouse 

 in their recent travels in those parts of the African continent, 

 and, further, go to show the enormous field for conchological 

 research awaiting the student of this veiy fruitful region, in 

 many parts of which it would appear that, probably owing to 

 variation in rainfall, altitude, etc., each range of hills has to a 

 certain extent its own special moUuscan fauna, often characterised 

 by certain local and peculiar phases not only common to the 

 species but also to the genera occurring in that particular 

 locality. 



Streptaxis percivali, sp. n. (PL XXXII. fig. 4.) 



Shell ovate, somewhat inflated, thin, semitransparent, yel- 

 lowish white ; whorls 5, the earlier whorls regularly increasing, 

 the later proportionately large, the last two distorted, sculptured 

 with fine, very oblique, and closely set costulse which become 

 obsolete on the base of the shell; suture impressed, narrowly 

 margined below ; umbilicus moderately narrow, deep ; columella 

 outwardly expanded, descending in a strong curve, dift'used above 

 into a thin, ill-defined, projecting callus which reaches the uj^per 

 margin of the labrum ; labrum white, narrowly expanded and 

 reflexed ; aperture somewhat oblique, roundly ovate. 



Alt. 9*25, diam. maj. 7, diam. min. 6 mm. 



Aperture : alt. 4, diam. 3-5 mm. 



Hah. Northern slopes of Mt. Marsabit, British East Africa 

 (A. Blayney Percival). 



Allied to S. kirkii Dohrn t, but difiering chiefly in having one 

 whorl less. 



Streptaxis woodhousei, sp. n. (PI. XXXII. fig. 5.) 

 Shell diflfering from *S'. percivali, to which it is nearly allied, 

 in its more rectangular and less inflated form, more obtuse apex, 



* For explanation of the Plates see p. 217. 

 t Proc. Zool. See. Lond. 1865, p. 232. 



