10 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



4. Paludestehsta Peraudieri (Bourguignat) ? 



Hydrohia Peraudieri, Bgt. : Spicil. Malac, p. 108 (1862); Malac. 

 Algerie, vol. ii, p. 227, pi. xiv, figs. 5-8. 



Sah. — On rushes growing in three feet of water, shallow bay of 

 lake, east of road, Wady Camp ; also on stones in shallow water, 

 Promontory Camp ; and dead from beach of Sand-spit, Taban Bay. 



I do not feel certain that all the specimens from the various 

 localities belong to one and the same species, as they exhibit some 

 variation in form, the convexity of the whorls, etc. They appear, 

 however, to agree closely with examples of this Algerian species, but 

 I cannot affirm that they are absolutely the same. In a genus where 

 the distinguishing characters are so few and not striking, the 

 identification of the species becomes extremely difficult, and it 

 really is necessary for one to study the genus as a whole before one 

 can understand at all clearly the distinctions between the various 

 species. Indeed, it is almost impossible from a study of the shells 

 only, and a knowledge of the animals is really necessary before one is 

 in a position to uphold or deny the validity of many so-called species 

 which have been described from the shells only. The Hydrohia 

 stagnalis, Linn., var. cornea, Eisso, quoted by Jickeli,^ may be the 

 same species. 



5. Yalvata nilotica, Jickeli. 



Valvata nilotica, Jickeli : Nova Acta Acad, Csesar. Leopold. Nat. 

 Curio., vol. xxxvii, p. 233, pi. vii, figs. 29a-c (1874). 

 Hab. — Beach of Sand-spit, Taban Bay, dead shells only. 



6. Melania tubercuiata (Mviller). 



Hah. — Dredged on mud in about one fathom, off mouth of bay east 

 of the "Wady and ofE East End Camp ; also dead shells from beach of 

 Taban Bay. 



7. Neeitika nilotica, Reeve, 

 Neritina nilotica. Reeve : Conch. Icon., vol. ix, figs. \b1a, h. 



Hah. — Beach near Kahk Camp, dead shells only. 



Martens is probably right in his supposition that N. arctilineata, 

 Sowerby, is the same as this species. 



8. IsiDORA CONTORTA (Michaud). 



Hah. — On reeds growing in swamp near mouth of "Wady, west 

 of road. 



9. Planorbis corntj, Ehrenberg. 



Hah. — On reeds growing in swamp near mouth of Wady, west of 

 road, and beach of Sand-spit, Taban Bay, 



1 Fauua Land- uad Sussw. Moll. Nord-ost-Afrika, p. 247, 



