148 Annals of the South African Museum. 



convex, rapidly increasing, sculpture very worn, apparently origin- 

 ally consisting of fine transverse striation, with faint malleation on 

 the later whorls. Suture deep, simple. Aperture rather small, 

 quadrately rounded ; peristome thickened and slightly reflexed, 

 the ends joined by a distinct callus, the outer lip making with 

 the body whorl an angle of 105° ; columella erect, margin strongly 

 reflexed, partly concealing the narrow perforation. 



Dimensions of Type : Alt. max. 24-5 ; diam. 20-2 ; apert. 

 13 X 10-9 mm. ; ends of peristome H-8 mm. apart. 



Animal of two full-grown specimens from Wilde Paards Hoek. — 



Colour (in alcohol) : head and foot tinged with grey, the hind end of 

 the foot being the darkest, mantle-edge grey to the left of the respira- 

 tory opening, but reddish and considerably swollen on the right side ; 

 roof of mantle-cavity unpigmented ; upper whorls light yellow above 

 the suture. Left body-lobe divided into two portions, which are 

 connected by a fold or ridge ; left division about as broad as the 

 right, but lower. Pulmonary veins : a second large branch of the 

 pericardial vein arises close to the origin of the first branch 

 (text-fig. 2, A). 



Cerebral ganglia covered with grey connective tissue. Jaw 

 2' 9 mm. long, rather thin, light brown ; resembling in form those of 

 the three following species (cf. PI. IV., figs. 18-20). Radula of the 

 same specimen (the shell of which measured 24 x 24 mm.) 6^ x 3|- mm. ; 

 transverse rows of teeth almost straight ; centrals very similar to the 

 laterals (text-fig. 2, B) ; formula, (53-f 1 + 53) x 133. Radula-sac 

 projecting beyond the buccal mass. 



Reproductive system (text-fig. 2, C) : hermaphrodite duct long, 

 swollen, and much convoluted ; vesicula seminalis unusually long, 

 rather broad distally but tapering proximally ; receptaculum seminis- 

 oval and unusually large ; receptacular duct somewhat swollen at its 

 anterior end ; vagina short, thicker behind than in front ; epiphallus 

 very short ; penis curved at the hind end ; rugae on the longitudinal 

 folds inside the penis much broader than long, as in the three 

 following species (cf. PI. IV., fig. 28). 



Ilab. Little Namaland. 



Type in British Museum. 



This species having been founded on a bleached, subfossil shell, 

 the original description is somewhat misleading. Some doubt, 

 moreover, attaches to the correctnsss of the original locality, the 

 fact that it was given as Springbok having led to a quite distinct 

 form, T. namaquensis , var. 2)roccrus, being confounded with gyjjsinus. 



A small series, collected by Dr. Rogers at Wilde Paards Hoek, 



