1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo © 309 
We have not seen hie interesting clam, which appears to belong to 
the Spheriide by its diminutive cardinal teeth, but differs by the rather 
solid, Corbicula-like shell with colored rays. The cardinal teeth have 
not been described in sufficient detail to admit of the needed comparison 
with Spherium, or to distinguish it from that genus. 
Only one species is known: 
_ Pseudocorbicula alluaudi DAuT&ENBERG, 1908, Journ. de Conchyl., LVI, p. 32, 
Pl. 11, figs. 8-10. Kavirondo Bay, in Lake Victoria. Length, 9.5 mm.; height, 8.5 
mm.; diameter, 6 mm. 
Donacidze 
This family is introduced with some hesitation to provide a place 
for the genera Egeria and Iphigenia. The former genus and the small 
species of the latter have usually been referred to the Cyrenide, the 
typical I['phigemz to the Donacide. 
The families Cyrenide and Donacide are placed in different super- 
families by Dall and in different suborders by Pelseneer. Unfortunately, 
the definitions given for these groups above family rank are nearly 
worthless in actual practice. | 
Kgeria and Iphigema differ from Cyrenide by their long siphons, 
by having the gills free throughout, not concrescent posteriorly as they 
are said to be in Cyrena and Corbicula, and by having longer labial palpi, 
In other external features the animals appear to be about as in Cyrenide. 
Donax (denticulatus Linnzeus) has the siphons decidedly longer than in 
Iphigenia. In both EHgeria and Iphigenza, there is a pallial sinus and the 
lateral teeth are developed in the right valve only and sometimes sub- 
obsolete. These two genera may be separated as follows: 
1. Pallial sinus ample, extending past the middle; hinge-plate narrow. 
3 I phigenva Schumacher. 
Pallial sinus small, not extending as far as the middle; hinge-plate broad. 
Egeria de Roissy. 
Eceria de Roissy 
Galatea BruGuizRE, 1797, ‘Encyel. Méthod, Vers,’ II, Atlas, Pl. cot (represent- 
ing the species subsequently described as Galathea radiata Lamarck). 
Galathea Lamarck, 1804, Ann. Mus. Hist. Nat. Paris, V, p. 431. Monotype: 
Galathea radiata Lamarck, 1804 = Venus paradoxa Born, 1780. Not Galathea Fabricius, 
1793. 
Egeria pe Roissy, 1805, ‘Hist. Nat. Gén. Partic. Mollusques,’ VI, pp. 324 and 
327. Monotype: Galathea radiata Lamarck (Dall, 1903, Trans. Wagner Free Inst. 
Sci. Philadelphia, III, p. 1453). 
Potamophila J. Sowrrsy, 1821,! ‘Gen. Rec. Foss. Shells,’ I, Pl. LXVI, with 
accompanying letter-press. Substitute for Galathea Lamarck. 
1The plate is dated ‘January 1821, published by Js. Sowerby.” 
