QUADRULA 933 
terior part of the disk without folds. Beaks approximate, 
eroded, a little in front of the anterior one-third of the length. 
Interior of the valves nacreous, shining, somewhat covered 
with microscopic granulations. Hinge very heavy; in the 
right valve two sulcate cardinals, of which the anterior is the 
larger and more projecting, and a single lateral, strong, ele- 
vated, angulated above and separated from the dorsal margin 
by a wide, deeply grooved space; in the left valve, two sulcate 
cardinals, of which the posterior is the larger and two lamellar 
laterals, separated from each other by a deep groove and from 
the margin of the shell by a rather large, deeply excavated 
space. Cicatrices of the adductor muscles small, rounded, well 
marked. Pallial impression entire, ascending anteriorly, where 
it separates gradually from the margin of the shell. Edge of 
the shell simple, sharp. Epidermis deep brownish-yellow, 
slightly fibrous towards the margin. Nacre white, not bril- 
liant and scarcely iridescent. 
Length 100, height 64, diam. 37 mm.” (D. and F.). 
Type locality, Song Bang-Giang a Cao-Bang, Indo-China. 
Unio (Quadrula) mansuyi DautzENBERG and H. Fiscuer, Jl. 
de Conch., LVI, 1908, p. 214, pl. VIII, fig. 5 and text-fig. 
“This species differs from U. leai by its posterior region 
obliquely truncate and acuminate at the post-basal extremity ; 
its sculpture is also different, consisting of folds subvertical in 
the centre of the disk and sharply diverging on the posterior 
slope; there are no isolated tubercles as in that species.” 
QuADRULA OVATA Simpson. 
Shell rather small, irregularly ovate, solid, inequilateral, in- 
flated; beaks apparently not very full or high; posterior ridge 
somewhat double, ending behind in a wide, nearly square bi- 
angulation: anterior end rounded; base lightly curved, outline 
of dorsal slope straight in front, curved behind; beaks corru- 
gated; carina spinose; epidermis greenish-black or chestnut, 
faintly rayed; pseudocardinals short, solid; nacre flesh-color, 
maculate with white. 
Length 45, height 28, diam. 20 mm. 
River Ning-Konofou, China. 
