436 Bulletin American Museum of Natural History (Vol. LIII 
Mutela joubini (Germain) 
Mutelina joubini GpRMaAIn, 1904, Bull. Mus. Hist. Nat. Paris, p. 470; 1908, in A. 
Chevalier, ‘L’ Afrique Centrale Frangeaise,’ p. 572, Lith. Pl., fig. 2. 
Mutela (Pseudomutela) joubini SIMPSON, pe CT ecuRnE, Cat. of N aiades,’ 
1363. 
Upper Ubangi River (type locality; A. Chevalier Coll.). 
Mutela lavigeriana Bourguignat 
Mutela lavigeriana Bourceuianat, 1886, ‘Nouv. Malacol., I, Un. et Irid. Tan- 
ganika,’ p. 26. 
Lake Tanganyika: (no more definite locality given). 
Mutela moncett Bourguignat 
Mutela monceti BouRGUIGNAT, 1886, ‘Nouv. Malacol., I, Un. et Irid. Tanganika, 
pe 20. 
Lake Tanganyika: (no more definite locality given). 
Mutela nilotica (Cailliaud) 
Plate XLII, Figure 1 
Iridina nilotica CaILLIAUD, 1823, ‘Voyage 4 Méroé,’ Atlas, II, Pl. ux, fig. 11; 
1827, op. cit., IV, p. 262 (type locality: ‘‘Canal de Joseph” in Lower Egypt). Férus- 
sac, 1823, Bull. Général Annonces et Nouv. Scientif., IV, p. 45 (without description). 
_ Sowersy, March, 1824, Zool. Journ., I, p. 53, Pl. 1. 
“Tridine du Nil” Drsuayrs, 1827, Mém. Soc. Hist. Nat. Paris, III, pp. 1-16, 
Pl. t (anatomy). 
Mutela nilotica “ Férussac and Sowerby”’ H. anp A. Apams, 1857, ‘Gen. Recent 
Moll.,’ II, p. 506. Simpson, 1900, Proc. U. S. Nat. Mus., XXII, p. 904; 1914, 
‘Descript. Cat. of Naiades,’ p. 1354. Grrmatn, 1909, Arch. Zool. Expér. Gén., XLI, 
p. 39, figs. 27-28; 1916, Bull. Mus. Hist. Nat. Paris, p. 204. J. Tauren, 1911, ‘Wiss. 
Ergebn. D. Z. Afr. Exp. (1907-08),’ III, p. 213. 
J. Thiele records this species from Lake Albert at Kassenje and from Lake 
Edward (Schubotz Coll.), but in all probability he had M. emini (v. Martens) before 
him. 
This species is not known with certainty from the Belgian Congo, 
and is here figured to discriminate it from the Lake Albert M. emini, 
which was described as a variety of nilotica. 
The specimen figured is from the Nile, and agrees very closely with 
Cailliaud’s figures, by which the species was originally defined. 
The shell is large, and one of the thickest, most solid Mutelz. The 
hinge is without teeth, the hinge plate rather heavy and rounded posterior 
to the beaks. The lower-anterior margin rises rather rapidly in some 
specimens, giving that end an oblique outline, a feature prominent in 
