976 NODUL ARIA 
tinct, faint. Dorsal cicatrices united to a groove situated at 
the inner side of the interval. Beak cavities shallow. Nacre 
silvery, iridescent. 
Length 43, height 25, diam. 16 mm.” (Haas). 
Type locality, Pisui, Hainan. . 
Nodularia undulata Haas, Ann. Mag. Nat. Hist., (8), VI, 
1910, p. 497; Con. Cab., Unio, 1910, p. 100, pl. x, figs. 2-3. 
Nopul,ARIA PERSCULPTA Haas. 
“Shell elongated, low, quite solid. Anterior end very short, 
semicircular ; ventral margin horizontal or slightly constricted, 
posteriorly bent upwards angularly to the lower angle of the 
posterior end; posterior margin first horizontal, then oblique ; 
the posterior point is biangulate, the lower angle being more 
pronounced than the upper. Beaks anterior, at 19/100 of the 
length, very prominent, swollen, their sculpture consisting of 
radial wrinkles, of which the central ones unite below forming 
a series of successive Vs. Ligament short, weak. Posterior 
slope low, distinctly defined. On the posterior ridge is a sys- 
tem of wrinkles, which extends in parallel, somewhat wavy 
lines both over the posterior slope and the posterior part of 
the disk almost to the ventral margin, these parallel lines 
meeting on the posterior ridge. In front of the posterior 
ridge the lines unite with the aforesaid V-shaped wrinkles ; 
the anterior portion of the disk is covered with weaker wrink- 
les, which are arranged on the edge of the areola as on the 
posterior ridge. This sculpture covers the whole surface in 
young shells and nearly all in the adults. Hinge rather weak; 
cardinal tooth of the left valve bifid, compressed, with a small 
triangular pit, in which arises a small tooth at right angles 
to the axis of the shell; cardinal tooth of the right valve tri- 
angular, cleft, with a fine vertical slit, in which the lamella 
in the pit of the left valve fits; laterals long, thin; one in the 
left valve, two in the right valve, a large one and the other 
only about half as large, situated at the rear half of the larger 
one. Cardinal teeth forming an angle of about 45 degrees 
with the axis; laterals parallel with the axis. Anterior muscu- 
lar impressions deep, funnel-shaped, posterior shallow. Nacre 
