Victoria Nyanza or Lake OuJcSrewS. 127 



Martens belong rather to one or other of Bourguignat's species 

 than to this Albert Nyanza form. 



16. Unio acuminatus, H. Adams. (PL XIT. fig. 12.) 

 Unto acmninatm, Martens, /. c. p. 105. 



Hah. South-west shore (Ji.) ; Albert Nyanza (Baker). 



As suggested by Bourguignat, this species is allied to the 

 U. Monceti of that author, and therefore it is not impossible 

 that the shells referred to it by Martens may really belong to 

 Aloncetiy as they come from the same lake. 



17. Unio Hauttecoeuri^ Bourguignat. 



Unio Hauttecoeuri, Bourguignat, 1883, Moll, fluv. Oukdr^we, p. 5, 

 figs. 1-3. 



18. Unto Grandidierij Bourguignat. 

 Unio Grandidieri, Bourguignat, /. c. p. 7, figs. 4-6. 



19. Unio EdwardsianuSj Bourguignat. 

 Unio Edicardsianus, Boui'guignat, I. c. p. 12, figs. 7-9. 



20. Uiio Duponti, Bourguignat. 

 Unio Duponti, Bourguignat, /. c. p. 8, figs. 10-12. 



21. Unio Grantianus, Bourguignat, 



Unto Grantianus, Bourguignat, /, c. p. 14. 



Of the five preceding so-called species it is impossible to 

 suppose that the variation in form and sculpture pointed out 

 by Bourguignat would be at all constant. At all events my 

 experience with regard to the Unionidai of the great Central- 

 African lakes proves that great variation both in outline and 

 ornamentation is constantly met with in many species. I am 

 therefore inclined to believe that these species of M. Bour- 

 guignat are merely variations of one and the same species. 



22. Unio Afoncetif Bourguignat. 

 Unio Monceti, Bourguignat, /. c. p. 15, figs. 13-15. 



23. Unio Ruellam, Bourguignat. 

 T'iiio Ituvllani, Bourguignat, /. r. p. 10, figs. 16-18. 



