1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 447 
There can be very little doubt that the type of this species is imma= 
ture, perhaps not half grown; but in our opinion its characters do. not 
permit union with any of the described forms. | 
Other Species of Pseudospatha Recorded from the Belgian Congo 
Pseudospatha bourguignat:. (Bourguignat) 
Burtonia bourguignati “Joubert”? Bourguienat, 1886, ‘Nouv. Malacol., I; 
Un. et Irid. Tanganika,’ p. 38; 1888, ‘Iconogr. Malacol. Tanganika,’ Pl. xxvi1, 
figs. 4 and 5. 
Pseudospatha bourguignati Bourguignat. Simpson, 1900, Proc. U. S. Nat. es 
XXII, p. 578; 1914, ‘Descript. Cat. of Naiades,’ p. 206. 
Lake Tanganyika: described from the lake without more definite locality. 
_Pseudospatha subtriangularis (Bourguignat) 
Burtonia subtriangularis Bourauienat, 1886, ‘Nouv. Malacol., I, Un. et Irid- 
Tanganika,’ p. 35; 1888, ‘Iconogr. Malacol. Tanganika,’ Pl. xxv, fig. 2. 
Pseudospatha subtriangularis Bourguignat. Simpson, 1900, Proc. U. S. Nat. 
Mus., XXII, p. 578; 1914, ‘Descript. Cat. of Naiades,’ p. 206. 
Burtonia grandidieriana BoureutieNnat, 1886, ‘Nouv. Malacol., I, Un. et Inrid. 
Tanganika,’ p. 42; 1888, ‘Iconogr. Malacol. Tanganika,’ Pl. xxv11, figs. 1-3. 
Lake Tanganyika: described from the lake without more definite locality. 
| _ Etheriide 
Fresh-water mussels with the shell conspicuously irregular, covered with a dark 
periostracum, attached to a solid substratum by one valve; nacreous within. The 
hinge is toothless; ligament deeply sunken. Having two adductor muscle impressions 
or only the posterior; pallial line entire. 
The mantle margins are united only to form an anal orifice; palpi large, semioval; 
foot degenerate or obsolete; gills like those of Unionide in form. 
This family comprises two genera in tropical South America, 
Bartlettia H. Adams (=Bartelettia Sowerby) and Acostea d’Orbigny 
(=Mulleria Férussac, 1828, not of Leach, 1814; Muelleria of some 
authors; Eumulleria Anthony, 1907); one in Africa and Madagascar, 
Etheria Lamarck; one in peninsular India, Pseudomulleria Anthony. 
Fossil forms are not known, but Etheria has been reported from supposedly 
Pleistocene deposits in Lower Egypt. 
ETHERIA Lamarck 
Etheria Lamarck, 1807, Ann. Mus. Hist. Nat. Paris, X, p. 400. ‘Dyes oy Gane: 
nation of Gray (1847, Proc. Zool. Soc. London, p. 193): Etherta semilunata Lamarck 
=F. elliptica Lamarck. 
ZAitheria BERTHOLD, 1827, in ‘Latreille’s Natirl. Fam. des Thierr.,’ p. 208. 
Emendation of EHtheria. 
