NODULARIA 1005 
striking form with an outline something like that of Plagiola 
elegans, though not quite so much cut away on the dorsal 
slope. 
Group of Nodularia contradens. 
Shell inflated, obovate, rhomboid. with a slight swelling at 
the post-base, and a well-developed posterior ridge; beaks 
full and high, the sculpture consisting of wavy, zigzag ridges, 
which often extend over the shell as somewhat nodulous cor- 
rugations ; pseudocardinals obliquely or vertically striate; lat- 
erals curved; cavity of the beaks rather shallow. 
NODULARIA CONTRADENS (Lea). 
Shell scarcely subsolid, subrhomboid or obovate, convex to 
subinflated, inequilateral; beaks but little elevated; posterior 
ridge inclined to be double, ending in a feeble biangulation 
at or below the median line; anterior end rounded, somewhat 
narrowed; base line curved, full behind the middle; dorsal 
slope obliquely truncate; surface with fine growth lines and 
indications of nodulous sculpture, the dorsal slope with faint, 
fine plications; epidermis dirty yellowish-green, darker and 
somewhat rayed behind the posterior ridge, subshining ; teeth 
much compressed ; laterals curved ; muscle scars shallow ; nacre 
bluish. 
Length 58, height 34, diam. 21 mm. 
Length 55, height 32, diam. 18 mm. 
Java. 
Unio contradens Lea, Tr. Am. Phil. Soc., VI, 1838, p. 75, pl. 
xvul, fig. 58; Obs., II, 1838, p. 75, pl. xvirt, fig. 58— Han- 
LEY, Biv. Shells, 1843, p. 200, pl. xx, fig. 8—CueENu, IIl. 
Conch., 1858, pl. xx1x, figs. 4, 4a, 4b—Rerve, Conch. Icon., 
XVI, 1865, pl. xxx, fig. 149. 
Margarita (Unio) contradens Lra, Syn., 1838, p. 25. 
Margaron (Unio) contradens Lea, Syn., 1852, p. 39; 1870, 
p. 46. | 
Nodularia contradens Simpson, Syn., 1900, p. 817. 
Contradens contradens Haas, Conch. Cab., Unio, 1912, pl. 
18, figs. 2-5. 
