254 MRS. JANE LONGSTAFF ON NON-MARINE 



I sent examples to M. Pallarv, and he suggested it might be a variety o£ 

 N. rugifer, Kiister, who^ however, calls his species the '^ runzeltragende 

 Flussperlmnschel/' and as I have just remarked^ my shells have no wrinkles ; 

 the shape also is different, the umbo being further from the anterior end, the 

 hinge-line shorter, and the posterior slope more gradual. 



Dimensions. — One specimen measures, long. 39'5, alt. 23, crass. 16*5 mm 

 Another is slightly shorter, the long, being 38 mm., while the alt. and crass. 

 are the same. 



Locality. — Lake Shambe„ Eighteen individuals. 



NODULARIA (C^latura) parretssi, PJiiUppi. (PL 18. fig. 8.) 



Unto 2'>arreyssi,Y. d. Busch in lit., Pliilippi, 1848, 'Abbildg. Besclireib.' vol. iii. p. 81, 



pi. 5. fig. 6. 

 Unio parreyssi, Kiister, 1862, ' Conch.-Cab.' p. 268, pi. 90. fig. 6. 

 ? Unio seniiaariensis , Kiister, ibid. p. 280, pi. 94. fig. 5 (uou fig. 6). 



About ninety specimens were taken between the mouth of the White Nile 

 and Lake No^ at the following localities : Mogran, Ad-Duwem, Tawila on 

 Abba Island, Masran Island, Gebel En, Mashra Zarafa AVood Station, south 

 of Melut, and Taufikiya. 



Philippi states that it occurred at Sennaar, White Nile {Kotschy). 



It has also been recorded from the Bahr el-Ghazal by von Martens. The 

 Swedish expedition found only one example in the White Nile, for which no 

 locality is given. According to M. Pallary, "Tres commun dans tout le cours 

 du Nil et de ses derives.'^ 



This species may be distinguished from JS. nilotim, Caill., with which it has 

 been united by some writers, by its more curved dorsal margin, lower posterior 

 rostrum, more flattened and generally more eroded umbo, the most swollen 

 part of the valve being lower, and by the thick and frequently jagged 

 anterior tooth in the right valve. The wrinkles vary as in iV. nilotica. A 

 young specimen from Mogran is remarkable for having wrinkles over the 

 umbo as well as on both ends. The colour of the nacre, however, is rarely so 

 deep in tone : it is white, white tinged with blue, purplish pink, coral pink, or 

 orange, the richest colour being within the umbo. The exterior is dark 

 brown, sometimes with a greenish or yellowish tint. It differs from 

 JSf. mossambicensis, Peters, in having the anterior end shorter and lower. 



Philippi's holotype measures, long. 42, alt. 25, crass. 16 mm. 



One of my shells from Ad-Duwem measures, long. 39-5, alt. at umbo 22*5, 

 greatest alt. 24'25, crass. 17 mm. 



A large individual from Mashra Zarafa Wood Station is dead and somewhat 

 worn, and I feel doubtful about referring it to this species, but it appears 

 more like it than any other. It measures, long. 43*5, greatest alt. 26-5, alt. 

 at umbo 25*5, crass. 19 mm. 



