pi ef reas Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian one 435 
The high wing and concave dorsal outline characterize this remark- 
able mussel. It varies in form of the posterior end, as will be seen by 
comparing our figure with Smith’s. 
Length, 91 mm.; height at beaks, 26 mm.; greatest height, 55 mm. } 
diameter, 13 mm. | 7 
Mutela emini (E. v. Martens) 
Plate XLII, Figures 2 and 2a 
Mutela nilotica var. emini E. v. Martens, 1897, ‘Deutsch Ost Afr., IV, Beschalte 
Weichth.,’ p. 253. Simpson, 1900, Proc. U. S, Nat. Mus., XXII, p. 904; 1914, 
‘Descript. Cat. of Naiades,’ p. 1355. 
Lake Albert: near Kassenje (Stuhlmann Coll.). E. v. Martens mentions that 
the valves of this mussel are used as spoons in Undussuma and among the Babira; 
he therefore supposes that the species may live in the Ituri River; but the isolated 
valves which the junior author saw on the Lendu Plateau were all said to come from 
Lake Albert. 
Lake Albert, western shore. 
The inflated shape, the brilliance of the deep to light corinthian red 
nacre, with red, green and violet reflections at the posterior end, and the 
more strongly inequilateral shape, distinguish this form from M. 
nilotica (Cailliaud). 
Length, 115 mm.; height at the beaks, 41 mm.; at posterior third, 47 mm.}; 
diameter, 40 mm. 
Under the microscope the nacre of this mussel is seen to be far 
smoother than that of M. nilotica. It is doubtless this which gives the 
glittering luster which characterizes emint. 
Other Species of Mutela, proper, Recorded from the Belgian Congo 
Mutela alluaudt Germain 
Muiela alluaudi Germain, 1909, Bull. Mus. Hist. Nat. Paris, p. 544, Pl. vir, 
fig. 45. Simpson, 1914, ‘Descript. Cat. of Naiades,’ p. 1366. 
Lake Albert: (type locality; C. Alluaud Coll.). 
Mutela angustata (Sowerby) 
Tridina angustata SowERBY, 1868, ‘Conchol. Iconica,’ XVI, Iridina, Pl. 11, fig. 5. 
Mutela angustata Sowerby. GERMAIN, 1906, Bull. Mus. Hist. Nat. Paris, p. 55° 
1913, op. cit., p. 293; 1908, in A. Chevalier, ‘L’ Afrique Centrale Frangaise,’ p. 564 
Originally described from Africa with doubt, the exact habitat unknown. Ger 
main has recorded it from the Lower Ubangi River (Poutrin Coll.), a highly doubtful 
record. This species is generally regarded as a synonym of M. dubia (Gmelin), but, 
to judge from the figure, it is distinct. 
Mutela chevaliert Germain 
Mutela chevalieri GERMAIN, 1904, Bull. Mus. Hist. Nat. Paris, p. 470; 1908, in 
A. Chevalier, ‘L’ Afrique Centrale Frangaise,’ p. 566, Lith. PL, fig. 1. 
Upper Ubangi River (type locality; A. Chevalier Coll.). 
