390 Bulletin American Museum of Natural History [Vol. LITT 
The beaks are rather low, at about the anterior two-sevenths of the length. 
The interior is white, bluish posteriorly. The pseudocardinal teeth are rather 
compressed, ragged, double in the left valve, where there is also an inter- dental 
tooth-like prominence. The laterals are thin and short. 
Length, 39 mm.; height, 23 mm.; diameter, 16 mm. Length from beaks to 
posterior end of the lateral teeth, 20 mm. 
While this species appears related to P. stuhlmanni (E. v. Martens), 
it differs by the straighter dorsal and ventral margins, the thinner shell, 
thinner teeth, less brilliant nacre, and other characters. 
Parreysia stuhlmanni (E. v. Martens) 
Plate XXXI, Figures 7-76 
Unio stuhlmannt i. v. Martens, 1897, ‘Deutsch Ost Afr., IV, Beschalte 
Weichth.,’ p. 231, Pl. vu, fig. 18. Grrmarn, 1916, Bull. Mus. Hist. Nat. Paris, p. 203. 
Parreysia stuhlmanni K. v. Martens. Simpson, 1900, Proc. U. S. Nat. Mus., 
XXII, p. 846; 1914, ‘Descript. Cat. of Naiades,’ p. 1126. 
Lake Edward: originally described from near Vichumbi, Kiruwe, and Katarenge, 
in the southwestern part of the lake (Stuhlmann Coll.). 
Lake Edward at Kabare (J. Bequaert Coll.). 
The shell is rather solid, inflated, long-ovate; the dorsal and basal margins about 
equally curved; the anterior end rounded, the posterior end prolonged, narrowly 
rounded. The epidermis is thin, brown (mainly worn off in our specimen). The surface 
has irregular growth lines, and near the beaks fine zigzag sculpture; there is also 
some corrugation on the dorsal slope anterior to the beak. There are also some in- 
distinct, weakly raised lines radiating from the umbonal region to the basal margin 
over the anterior part of the valve. The beaks are rather low and wide, the tip at 
about the anterior two-sevenths of the length, nodular in two series, this sculpture 
soon giving place to zigzag ridges. The interior is bright silvery, with red and green 
reflections. Pseudocardinal teeth double in the left valve, deeply cut, or ‘“‘ragged.”’ 
Lateral teeth short, hardly one-third the length of the shell; interdental plate 
moderately developed. 
Length, 42.5 mm.; height, 27.5 mm.; semi-diameter, 10.5 mm.; 20.0 mm. from 
beak to posterior end of the lateral teeth. 
This is a longer, plumper shell than P. ngestana, with a more pointed 
posterior end and less extensive corrugation, which became obsolete 
when the shell had reached a length of about 14 mm. 
A new description is given as the specimen here figured differs a 
little from that described by von Martens. However, we believe that 
such differences as appear are individual rather than racial. 
Parreysia leopoldvillensis (Putzeys) 
Plate XX XI, Figures 1-4 
Unio leopoldvillensis Purzmys, Ann. Soc. Malacol. Belgique, XXXII, Bull. 
Séances, p. xxvii, figs. 12 and 13. 
