958 NODULARIA 
times a little angled above; base line very slightly curved, 
quite full near the posterior end; surface with irregular growth 
lines, but with no other sculpture in the specimens seen; epi- 
dermis brownish, cloth-like ; pseudocardinals triangular, two in 
the left valve, one and a compressed one in the right; laterals 
long, slender, straight ; muscle scars rather shallow, the hinder 
ones slightly elongated; nacre bluish, dirty brownish in the 
cavities. . 
Length 65, height 20, diam. 12 mm. 
Japan. 
Unio oxyrhynchus von Martens, Mal. Blatt, VII, 1861, p. 57. 
—Koseutr, Abh. Senck. Nat. Ges., XL, 1879, p. 420, pl. x11, 
figs. 3, 4.—PFEIFFER, Nov. Conch., V, 1879, p. 192, pl. CLV1I, 
figs. 4, 6. 
Nodularia oxyrhynchus SIMPSON, Syn., 1900, p. 807. 
Lanceolaria oxyrhyncha Haas, Con. Cab., Unio, 1910, p. 53, 
plea, tress ie 2s 
Less solid, more compressed and higher than any of the 
related species. In all the examples I have seen there is only 
irregular, concentric sculpture, though it is probable that some 
specimens might show traces of corrugation. 
Section CYLINDRICA Simpson, Igoo. 
Cylindrica SIMPSON, Syn., 1900, p. 807. 
Shell inflated, solid, cylindrical, smooth, with a rounded pos- 
terior ridge; teeth heavy, pseudocardinals radiate, curved. 
Type, Nodularia cylindrica Simpson. 
NODULARIA CYLINDRICA Simpson. 
Shell greatly elongated, inflated, rather solid, slightly ar- 
cuate, very inequilateral, rounded in front, with a low, round- 
ed posterior ridge, which ends behind in a rounded point near 
the base line; the dorsal slope is obliquely truncated ; ligament 
large, long; surface apparently without sculpture, with the 
exception of slight, concentric ridges; epidermis thick, brown; 
dorsal line wavy at the hinder end where the point is turned 
