242 MRS. JANE LONGSTAFF ON NON-MARINE 



and at Hillet al-Nuvver (one). They were near the edge of the river and are 

 small. M. Pallary, who kindly examined them^ considers them immature. 

 One from Gebel En has the spire more produced and resembles L. acroxa, 

 Bourg. (op. cit. fig. 94), which M. Pallary also thinks is an immature stage 

 of this species. He states that L. cailliaudi is found in the " Cours du Nil 

 Bleu et du Grrand Nil." He has not, however, recorded it in his descriptions 

 of the Innes Bey Collection ; neither has the Swedish Expedition noted its 

 occurrence in the White Nile. Bourguignat reports it in addition from Lake 

 Dembea. 



This seems to be a new record of its existence in this region. 



Genus Planorbis, Giiettard. 



Planorbis BOissYi, Pot. et Midi. 



Planorbis boissyi, 1838, Potiez et Micliaud, ' Galerie de Douai,' vol. i. p. 208, pi. 2], 

 figs. 4-6. 



I met with this species both to the north and'south of Lake No, and took 

 eighteen specimens in all : at Abba Island (two) , Hillet Abbas (four), Grebel 

 En (five), north end of Bahr el-Zarafa (three), south end (one), and Hillet 

 al-Nuwer (three). The Swedish Expedition appear to have l)een the first to 

 find it in the White Nile, and they obtained numerous young examples at 

 Gebel Ahmad Agha, none of which is as large as my biggest, which 

 measures, alt. 3*5, diam. 12 mm. This species is also recorded from Lower 

 Egypt. 



Planorbis mareoticus (Letourn. MS.), Innes. 



Planorbis niareoticus, 1884, Walter Innes, Bull. Soc. Malac. France, vol. i. p. 339. 



Only one dead specimen in Lake Shambe, which I sent to M. Pallary, who 

 kindly determined it. He had previously recorded some examples of the 

 species found by Dr. Innes Bey in the marshes of the White Nile. 



It is doubtful whether this should be separated from P. elirenhergi, Beck 

 (P. cornu, Ehrenb.). Dr. Innes Bey and M. Pallary consider the species 

 distinct, restricting the name ehrenberc/i to specimens with convex whorls 

 and mareoticus to those with sharply keeled whorls. Jickeli and M. Ancey 

 regard them as conspecific because there are numerous intermediate forms. 



Prof. Schweinfurth took specimens of P. cornu, Ehrenberg (which is 

 probably identical with this) in the Bahr el-Ghazal. It also occurs in 

 Lower Egypt. 



