QUADRULA 915 
Group of Quadrula messageri. 
Shell subquadrate, almost squarely truncated behind, having 
a few wavy, almost longitudinal folds on the upper part of the 
disk. 
QUADRULA MESSACERL (Bavay and Dautzenberg). 
Shell subquadrate, solid, inflated, inequilateral, with low, 
but apparently inflated, beaks, whose sculpture is not known ; 
posterior ridge full and rounded, ending behind at or near the 
base line; above it there is a wide, very shallow, radial de- 
pression; posterior end of the shell almost squarely truncated ; 
dorsal and basal lines slightly and similarly curved toward the 
somewhat narrow, rounded anterior end; surface sulcated an- 
teriorly, nearly smooth behind and below, having a number 
of rather strong, wavy, almost longitudinal, folds on the upper 
part of the disk; epidermis yellowish-brown, faintly rayed ; 
pseudocardinals ragged; laterals curved; nacre whitish, tinted 
bronze. 
Length 44, height 31, diam. 20 mm. 
Lang-Son and That-Khe, Indo-China. 
Unio messageri BAvAy and DautTzeNBERG, Journ. de Conch., 
OLEXS 1001; pay) pl: 1.figss 3,4. 
Protunio messageri Haas, Conch. Cab. Unio, 1912, pl. 32, figs. 
T-2. 
Apparently a Ounadrula related to the Chinese forms and 
bearing some resemblance to depauperate, rather smooth, 
specimens of O. undulata and perplicata of the Mississippi 
Valley. The strong longitudinal or very slightly oblique folds 
on the upper part of the disk recall the American species. 
Haas has recently, (Nachr. Deutsch. Mal. Ges., 1913, p. 37), 
made this species the type of a new genus, Protunio. 
Group of Quadrula nodulosa. 
Shell very solid, oval or rounded, inflated, inequilateral, in- 
equtivalve, the valves more or less twisted on their axis or hav- 
ing the appearance as if one of them had been pushed for- 
ward on the other, so that a dorsal view shows the outline to 
