166 Annals of the SoiUh African Museum. 



known species of Dorcasia. They have neither the continuous 

 peristome of alcxandri nor the open umbilicus and comparatively 

 small aperture of cernua, while coagulum is a more globose form, 

 with more rapidly increasing whorls. 



In many features of its internal anatomy D. rogersi bears a close 

 resemblance to D. coagulum. The radula, however, is very distinct ; 

 for not only are there fewer teeth in each transverse row, but the 

 shape of the teeth is different, the inner marginals being quite unlike 

 those of D. coagulum, as will be seen from the figures. The repro- 

 ductive organs are very simple, the relatively small size of the penis 

 being, perhaps, the most characteristic feature. 



I should not be surprised to find that the new species is 

 more nearly allied to D. cernua, when live examples of the last- 

 named are available for examination ; the difference in the umbilicus 

 and aperture, however, should always afford means of distinction. 



Dorcasia cernua (von Martens). 



(PL III, f. 4.) 



1889 Helix cerium, von Mts., Sitz.-Ber. Ges. Nat. Fr. Berlin, 

 p. 161. D. 



Shell large, flat, deeply umbilicate, rather thick and solid, but 

 translucent, type bleached white, but exhibiting faint traces of 

 mottling, which would probably represent patches of colour in a live 

 specimen. Spire hardly raised. Whorls 5h, rounded, gradually 

 increasing, the last descending so abruptly and steeply in front that 

 when the empty shell rests in its natural position the interior can 

 hardly be seen ; surface almost smooth, the fine, close, regular 

 transverse striation, which is present on all but the first li whorls, 

 being only just visible without a lens. Suture shallow. Aperture 

 comparatively small, ovate ; peristome thickened and reflexed, ends 

 joined by a thick callus. Umbilicus wide and deep, extending to 

 the apex. 



Dimensions of Type : Diam. maj. 30-5, min. 24-5 ; alt. max. 12-5 ; 

 apert. 14-3 x 10-7 mm. ; ends of peristome 5*5 mm. apart. 



Animal unknown. 



Hab. Great Namaland. Angamthal ; Kuibis ; Eooiberg (sub- 

 fossil). 



Type in Berlin Museum. 



With this is another subfossil shell from Eooiberg, near Bethany. 

 It is much smaller than the Type, spire more raised, sculpture slightly 

 more pronounced, whorls 5, the last not descending so far nor so 



