the Victoria Nyanza or Lake Oukerewe. 383 



peristoma tenue, intus iiigro-purp\ireum, infernc leviter efFusum, 

 ad ooliimcllam vix reflexiim, marginibiis callo plus minus atro- 

 purpureo junctis. 

 Alt. 54 millim., diam. maj. 52, min. 37 ; apertura 44 longa, 

 27 lata. 



Hah. Victoria Nyanza (south end?). 



Tlie single shell which I have named after Mr. Gordon 

 does not appear to be the young of A. nyanzcn. It is much 

 more narrowly umbilicated, has a sliorter spire and a larger 

 aperture. The latter is of a much darker colour, the colu- 

 mella and the inside of the outer lip are ])ur))lish black, and 

 tlie external spiral narrow zones are more distinct. 



Planorhis victorice. 



Test a inferno late et profuude umbilicata, supra minus profunde et 

 angustius excavata, mediocriter inflata, lineis increment! obliquis 

 striata, olivacea ; anfractus 3-4, celeriter crescentes, ultimus su- 

 perne et ad peripheriam rotundatus, infra circa unibilicum com- 

 presse angulatus vel carinatus, antice subdescendens ; apertura 

 mediocriter magna, fusca, supcrue lata, infcrne angustata, rccedeus ; 

 peristoma (latoraliter visum) obliquum. 



Diam. maj. >! millim., min. G, alt. 4. 



Hob. North end of the lake. 



This species apparently is distinct from Ph choanomphahiSy 

 Martens, also from Lake Victoria. It has no upper or peri- 

 pherial angle, and the lower side is more deej)ly umbilicated 

 than the ujjper. 



Sphcermm nyanza'. 



Testa rotunde ovata, solidiuscula, mediocriter globosa, straminea, 

 umbones versus leviter erosa, sukequilateralis, striis concentricis 

 tenuibus sculpta ; latus anticum rotundatum, posticum paulo 

 latius ; umbones parura prominentes, obtusi, mediani ; deutes 

 cardinales mediocres, laterales validi : pagina interna albida, 



Longit. 7 millim., alt. 0, diam. 4-1-. 



Hah. North end of tlie lake. 



This species is of rather solid texture, of a straw-colour, 

 and only faintly striated. The lateral teeth are strongly 

 developed for so small a shell. S. capense^ Krauss, is thinner 

 and has a more feeble dentition. 



