PUPILLA, AFRICA. 217 



short and straight. There is sometimes a minute, tubercular 

 angular lamella a short distance below the insertion of the 

 outer lip. The parietal callus is very thin and transparent. 

 The lower-palatal fold is large, the upper small or very small. 

 Short and long examples measure : 



Fig. 10. Length 3, diam. ab. apert. 1.45 mm.; 5*4 whorls. 

 Cradock. 



Fig. 9. Length 3.55, diam. ab. apert. 1.5 mm. ; 5% whorls. 

 Coega. 



The original specimens of P. tetrodus were decidedly stouter 

 in figure than the recent form, (sinistrorsa = thaumasta) if we 

 may judge by Boettger's figures, reproduced in pi. 17, figs. 

 14-16. Unfortunately he gave no measurements, but indi- 

 cates on the plate that they are magnified 7 times ; this would 

 make tetrodus 3 mm. long, very nearly 2 wide. The figures 

 show also an external impression of the last whorl over the 

 palatal region deeper than the flattening to be seen in the 

 recent form. The shape of the aperture also is somewhat 

 different. It is not impossible that Boettger's figures are in- 

 correct. He drew freehand, usually with great accuracy, 

 though often rather diagrammatically. In his later work 

 Boettger mentions specimens from Gobabis, Damaraland, 

 measuring 3 x li/o mm., agreeing in size, he says, with the 

 originals. 



Craven's Pupa (Vertigo) sinistrorsa is the ordinary living 

 form. The original description follows. 



Shell sinistral, subperforate, ovately conical, of a horny 

 brown color, paler near the apex, rather glossy, faintly stri- 

 ated by the lines of growth; whorls 5y 2 , very convex, grad- 

 ually increasing, the last two equal in diameter; suture deep 

 and well defined; aperture nearly circular, armed with four 

 internal teeth, viz. : one large tooth situated on the paries near 

 its centre, another smaller tooth on the columella far within 

 the aperture, another at the base of the outer lip, and a very 

 small one at its centre ; labrum outwardly reflexed ; extremi- 

 ties of peristome connected by a thin callosity. Length 3 to 

 3% mm., greatest diameter 2, diameter of aperture 1 (Craven}. 



