58 Mr. H. B. Preston on 



Hypocaccus various } Sell., 1890. 



This species, first discovered in Japan, and latter in China 

 and Ceylon, has now been found in Australia at Sand Islet, 

 Long Reef. Some examples have the marginal stria of the 

 mesosternum interrupted anteriorly. The Australian speci- 

 mens are in the British Museum : all have the sutural dorsal 

 stria abbreviated. As its name indicates, its sculpture is 

 extremely variable. 



Hypocaccus apricarius, Er. 

 Heir C. Bruch has found this species at Montevideo. 



VII. — Further Additions to the Molluscan Fauna of Central 

 Africa. By H. B. Preston, F.Z.S. 



[Plates IV. & V.] 



Helicarion perfragilis, sp. n. (Fig. 1.) 



Shell ovate, thin, transparent, shining, amber-colour ; 

 whorls 3, rapidly increasing in size, the last dilated below, 

 marked with indistinct growth-lines ; sutures scarcely im- 

 pressed, very narrowly margined ; labrum acute ; aperture 

 large, ovate, elongately dilated. 



Alt. 4'25, diam. maj. 8'25, diam. min. 6 mm. 



Aperture : alt. 4, diam. 5 mm. 



Hab. Maringo Plateaux, Belgian Congo. 



Thapsia gereti, sp. n. (Fig. 2.) 



Shell discoidal, thin, hyaline, rather opaque, pale greyish 

 white ; spire somewhat elevated ; whorls 0^, marked with 

 transverse growth-lines, which become more noticeable on the 

 base ; sutures impressed, narrowly margined ; umbilicus 

 narrow, deep; peristome descending very obliquely; labrum 

 simple, acute ; aperture obliquely broadly lunate. 



Alt. 3, diam. maj. 5'75, diam. min. 5 mm. 



Aperture : alt. 2, diam. 2 mm. 



Hab. Maringo Plateaux, Belgian Congo. 



Allied to T. mixta, Smith, from Chiradzulu, Nyika Plateau, 

 British Central Africa, but more closely coiled and with the 

 spire more elevated than in that species. 



