446 Bulletin American Museum of N atural History [Vol. LIII 
cluded by Bourguignat in his P. livingstonana. The beaks have the 
same sculpture as tanganytcensis but somewhat finer and weaker. 
Length, 62.0 mm.; height, 25.0 mm.; diameter, 7.0 mm. 
This form may turn out to be a mere mutation of P. tanganyicensis, 
rather than a separate race. 
Pseudospatha ortmanni, new species 
Plate XLV, Figures 5 and 7 
Lake Tanganyika: Bay of Toa in 5 m. (Station 1163; Stappers 
Coll. Type 132188 A.N.S.P.); Tembwe (Hubert Coll.); Moliro 
(Pilette Coll.). : 
The shell has the usual compressed form and polished surface. It is widest near. 
the middle, the ventral border strongly convex. Anterior end oblique, being produced 
forward in the neighborhood of the hinge. Posterior end obtusely rounded, the 
margins tapering to it above and below. The beak shows a minute, rounded glochidial 
shell, after which it is finely concentrically striate, the strize gradually becoming coarser 
on the rest of the valve. The low posterior ridge shows one or two very low radial 
welts. The color is pale yellow near the borders, becoming hydrangéa pink toward 
the beaks. ‘The hinge-plate is very narrow, but bears narrow, distinctly raised 
lateral and anterior ridges, single in both valves. The whole interior is hydrangea 
pink. 
Length, 43.0 mm.; height, 17.5 mm.; diameter, 5.3mm. ‘Toa; type. 
see 2) si Ee A 5.3 Tembwe. 
Soto OO ihe bo. Q ‘ 9.0 Moliro. 
This species is separated from P. tanganyicensis chiefly on account 
of the diverse beak sculpture, but it differs somewhat also in outline, in 
color, and in the narrower hinge-plate. 
It is named for Dr. Arnold E. Ortmann, in recognition of his in- 
portant work upon the anatomy of fresh-water mussels. 
Pseudospatha stappersi, new species 
Plate XLV, Figure 6 
Lake Tanganyika: bay of Kilewa, in 12 m. (Stappers Coll. Type 
132189 A.N.S.P.). 
The shell resembles P. ortmanni by lacking distinct beak sculpture. The beaks 
are finely, weakly striate around the subcircular, convex, densely microscopically 
granulose glochidial shell. The height is less than in P. ortmanni, only one-third of 
the length. The anterior margin is truncate, not oblique in the upper pari, and the 
posterior end is longer. The color is yellow toward the margins, pale and subtrans- 
parent toward the beaks. 
Length, 32.38 mm.; height, 11-0 mm.; diameter, 3.7 mm. 
