1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 409 
Off Lukonzolwa in Lake Moero (Stappers Coll.). Stappers obtained 
it at several other places in the lake and also in the Luapula River at 
Kachiobwe. 
Fig. 90. Pseudavicula johnstoni (Smith). Lukonzolwa Lake Moero. 
This peculiar mussel has been compared to H 'yriopsis bialata Simp- 
son (= Unio delphinus Gruner) and to Prisodon obliquus (Schumacher), 
Whether it is related to the Oriental genus or the South American re- 
mains doubtful. By the bialate form it approaches Pseudospatha, 
which is otherwise quite different. 
The specimen figured i is 50 mm. long. 
Unionide of Doubtful Affinity 
_ The following species of “‘ Unio,’”’ all described by Bourguignat from 
the western shore of Lake Tanganyika, north of the Lukuga River, 
have not been ii and it is a cehaee to place them in the modern 
genera. | 
Unio bri ouxt Bourauianat, 1886, ‘Nouv. Malacol., I, Un. et Irid. Tanganika,’ 
py. 18: ‘eee 
Unio guillemeti BoURGUIGNAT, 1886, op . cit., p. 15. 
Unio josseti BoURGUIGNAT, 1886, op. cit., p. 19. 
Unio jouberti BoURGUIGNAT, 1886, op. cit., p. 8. 
Unio lavi erianus BouRGUIGNAT, 1886, op. cit., p. 14=Unio lavigerinus Simp- 
son, 1900, Proc U.S. Nat. Mus., XXII, p. 862. : 
Unio menardi BouRGUIGNAT, 1886, op. cit., p. 20. 
Unio moinett BOURGUIGNAT, 1886, op. cit., p. 11. 
Unio vincket BOURGUIGNAT, 1886, op. cit., p. 18. 
Unio visserti BoURGUIGNAT, 1886, op. cit., p. 21. 
Mutelidee 
Platiris I. Lea, 1838, Trans. American Phil. Soc., N.S., VI, pp. 118 and 141, 
Lea’s genus Platiris included the Mutelide known at its date. 
Mutelidz and Mycetopine H. anp A. Apams, 1858, “Gen. Recent Moll.,’ II, 
pp. 505 and 504. 
Iridinidee BourcuieNat, 1886, ‘Nouv. Malacol., I, Un. et Inid. Tanganika,’ p. 24. 
