402 Bulletin American Museum of Natural History [Vol. LIT] 
Germain (1908, in A. Chevalier, ‘L’Afrique Centrale Frangaise,’ 
p. 542) has described a var. minor of this species from the Bangoran and 
Mamun Rivers, French Equatorial Africa. 
Celatura gerrardi (EH. v. Martens) 
Plate XXXII, Figures 1 and la 
Unio gerrardi E. v. Marrens, 1897, ‘Deutsch Ost Afr., IV, Beschalte Weichth.,’ 
Dp. 220, Fl. Val, Ne. o. 
Nodularia nilotica var. gerrardi E. v. Martens. Simpson, 1900, Proc. U.S. Nat. 
Mus., XXII, p . 822. ‘ , 
Nodularia (Czlatura) gerrardi E. v. Martens. Simpson, 1914, ‘Descript. Cat. of 
Naiades,’ 1914, p. 1022. 
Lake Tanganyika: originally described from the lake without more definite 
locality. 
According to E. v. Martens this is probably the species recorded from Tangan- 
yika as “Unio niloticus” by E.:A. Smith (1880, Proc. Zool. Soc. London, p. 351; 
1881, op. cit., p. 296). ' 
Unio gerrardi was described from two single valves, the one figured 
having lost much of the epidermis. A specimen collected by Stappers 
in Lake Tanganyika is now figured. The color is fuscous, shading to 
blackish below, more cinnamon toward the beaks. ‘The beaks have two 
radial series of tubercles, much smaller than in C. egyptzaca, with groups 
of close folds in front and behind, these folds converging somewhat 
downward. 
Length, 44.0 mm.; height, 30.0 mm.; diameter, 20.0 mm. 
Celatura mesafricana, new species 
Plate XXXII, Figures 2 and 2a 
Garamba River (Lang and Chapin Coll.), February, 1913. 
The shell is rather thin, oblong, inflated. The dorsal and ventral margins are 
subparallel; anterior end rounded, posterior end obliquely truncate. The posterior 
ridge is rounded. Olive-brown, having two narrow, indistinct green rays on the 
posterior slope and with an irregular, honey-yellow patch posteriorly. The surface is 
somewhat shining, striate finely and irregularly, the strize with fine cuticular edges; 
these strize are more prominent on the posterior slope. On the half of the posterior 
slope nearer the beaks there is fine, curved corrugation running toward the ligament 
(and in young shells traces of narrowly double-looped corrugation may be seen near 
the beaks in the median part, and oblique corrugation posteriorly). The beaks are 
eroded in all specimens seen. The interior is pale blue near the edges, pinkish in the 
cavity. The pseudocardinal teeth are much compressed, double in the right valve. 
In the left there is a well-developed tooth and farther back, nearly under the beaks, 
a subobsolete tooth. Laterals well developed but compressed. 
