4 
1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo © 391 
Parreysia leopoldvillensis Putzeys. Simpson, 1900, Proc. U, 8, Nat.. Mus., 
XXIT, p. 846; 1914, ‘Descript. Cat. of Naiades,’ p. 1124. 
Sinnley Pool near Leopoldville (type locality). 
Zambi and Stanleyville in the Congo River; Faradje in the nee 
River (Lang and Chapin Coll.). Avakubi in the id River (J. Bequaert 
Coll). | 
A somewhat rhombic, solid species, higher posteriorly, with sculp- 
ture of fine zigzag ridges over the upper third or half, below which they 
are concentric. In occasional examples the pseudocardinal teeth are 
lacerated (Fig. 86a), much as in Grandidieria. In specimens from Zambi 
the height of the shell varies from 66 to 70 per cent of the length. 
Length, 33.0 mm.; height, 22.0 mm.; diameter, 13.2mm. Zambi. 
a 99.6 os yg «6 
‘ 39.0 Hi GAN Lene 14.3 " 
Many specimens from Stanleyville and Avakubi do not differ from 
those of Zambi (Pl. XX XI, figs. 1-3). The constancy of the species 
over so great a range is remarkable. Putzeys gives the dimensions of 
the Stanley Pool types as: length, 45 mm.; height, 28-30 mm.; diam- 
eter, 15-19 mm. These are larger than any of the long series before us. 
a | b 
Fig. 86. Parreysia leopoldvillensis (Putzeys). Hinge teeth of specimens from: 
a, Zambi, and b, Stanleyville. 
A young shell is figured to show the sculpture pattern, which is 
more or less obliterated in adults (Fig. 87). 
In specimens from Faradje (Pl. XX XI, fig. 4) the shell is relatively 
higher than in leopoldvillensis, the height about 73 per cent of the 
length, and the basal margin is more curved. Length, 29.5 mm. ; height, 
21.5 mm.; diameter, 12.2 mm. 
