TRUNCATELLINA OF SOUTH AFRICA. 



91 



Key to South African Species. 



1. Aperture having parietal, columellar and palatal teeth.. 



T. perplexa, no. 24. 

 No parietal lamella or tooth 2. 



2. Surface nearly smooth or quite weakly ribbed. 



T. sykesi, no. 29. 



Surface very finely striate ; no palatal tooth ; 1.87 x 0.9 mm. 



T. quantula, no. 27. 

 Surface subregular rib-striate 3. 



3. Aperture with an immersed palatal tooth 4. 



No palatal tooth 5. 



4. Length 1.3 to 1.6 mm., 5y 2 whorls. T. pretoriensis, no. 25. 

 Length 1.85 to 2.4 mm., 6% to 8% whorls. 



T. iota livingstonensis, no. 28a. 



5. Length 2 mm. or more, 7 1 / 2 i whorls T. iota, no. 28. 



Length 1.57 mm., 5i/o whorls T. dysorata, no. 26. 



24. TRUNCATELLINA PERPLEXA (Burnup). PI. 9, figs. 24, 25. 



Shell very small, umbilicate, cylindrical, thin, translucent, 

 shining ; pale brown ; spire cylindrical, rounded above ; sutures 

 impressed ; apex obtuse ; whorls 6, very convex, closely trans- 

 versely lirate, except the first two which are smooth ; the shell 

 at the fourth, fifth, and sixth whorls of nearly equal width, 

 the last half-whorl acquiring its greatest expansion a little 

 below the suture and then being flattened beneath, forming 

 an infrasutural angle, the last whorl compressed towards the 

 umbilicus. Aperture rounded, nearly % the height of the 

 shell ; peristome whitish, reflexed, especially at the columellar 

 margin, thickened, the ends converging and connected by a 

 thin callus; labrum [outer lip] slightly incurved about the 

 middle; columella straight. The processes of the aperture 

 consist of a small white parietal plait running inwards and 

 there becoming strong, a stout white post-columellar plait, also 

 running inwards, and a profoundly post-labral [palatal] 

 tooth or plait hidden by the columella (Burnup). 



Fig. 24. Type : height 1.72, width 0.82 mm. 



Fig. 25. (sectional) : height 1.80, width 0.77 mm. (Burnup). 



Cape of Good Hope: Cradock; Port Elizabeth (Farquhar). 



