MOLLUSOA FROM THE SOUTHERN SUDAN. 237 



111 order to save space I have only given sufficient references to identify 

 each species. Also, A\'ith a few exceptions, only the names of works on the 

 subject published since 1908, as Herr Hagg and M. Pallary have compiled 

 complete lists of those pi'ior to that date. 



Class GASTEROPODA. 



Order PROSOBRANCHIATA. 



Suborder MONOTOCARDIA. 



Section TaBjiioglossa. 

 Family H Y D R B 1 1 D ^. 

 Subgenus G-abbia, Tryon. 



GrABBIA SENNAAKICA, Kuster. 



Paluclina sennaarica, Parreyss in Kiister, 1853, ' Syst. Conchy l.-Cab.' p. 44, pi. 9. fig. 10. 



Grebel En (two), Bahv el-Zarafa (five), small living specimens numerous 

 amongst weeds in Lake Shambe, and Kanisa (one). Confirmed by M. Pallary. 

 He states that the species occurs " Tout le cours da Nil efc de ses affluents.-" 

 Bourguignat records it from Abyssinia and the Blue Nile. 



The largest example was found at Gebel En ; it measures, alt. 5 "75, 

 diam. 4 mm. Another from Bahr el-Zarafa is nearly as big, measuring- 

 alt. 5"5, diam. 4 mm. 



The specimens from these two localities have the spire slightly higher 

 than some I got in ponds near the Pyramids of Gizeh, which M. Pallary 

 considered typical. 



Family ViviPARiDiE. 

 Genus Vivipara, Lamarck. 



YlVIPARA UNICOLOR, OUv. 



Cyclostoma unicolor, Olivier, 1804, 1812, ' Voy. Emp. Ottoman,' vol. ii. p. 39, vol. iii. p. 68, 

 Atlas ii. pi. 31. fig. 9. 



Thirty-five specimens were taken at the following localities: — near Mogran 

 (six), Abba Island (six), Ad-Duwem (one), Hillet Abbas (five), Masran Island 

 (two), Gebel En (three), Kodok (one), Waw (one), Hillet al-Nuwer (two), 

 and in Lake Shambe (eight). 



