IO14 NODULARIA 
The beaks are fuller and higher than those of U. dautzen- 
bergi; the dorsal slope is not truncated; the sculpture on the 
disk is not so rude or nodulous. 
NopDULARIA TUMIDULA (Lea). 
Shell long ovate, subinflated, subsolid, inequilateral; beaks 
high and full, with a large lunule in front of them; posterior 
ridge low, angular above, somewhat double below, ending in a 
faint biangulation below the median line; anterior end round; 
base line almost evenly curved, but slightly produced behind 
the middle; surface almost smooth, with some feeble corruga- 
tions and wrinkles on the dorsal slope; epidermis dirty yellow- 
ish-green, with two or three faint, dark rays on the dorsal 
slope; hinge line almost evenly curved; teeth delicate ; pseudo- 
cardinals compressed; laterals wavy; muscle scars well mark- 
ed: beak cavities impressed; nacre bluish-white, inclining to 
iridescent. 
Length 49, height 27, diam. 18 mm. 
Siam ; Cambodia. 
Unio tumidulus Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 93; 
Obs., VI, 1857, ps 15. pl. Xv, tis, 9 = | Ac NE Sere eines 
IIT, 1858, p. 295, pl. xxv, fig. 9.—Sowrrpy, Conch. Icon., 
XV 1) 1868, plouxaca x, fies G2" 
Margaron (Unio) tumidulus Lea, Syn., 1870, p. 39. 
Nodularia tumidula Stmpson, Syn., 1900, p. 814. 
Oxynaia tumidula Haas, Con. Cab., Unio, 1910, pl. 14, fig. 4. 
I have only seen the type, a dead shell, and not in excellent 
condition. ‘his species does not seem to be very closely re- 
lated to any other, but after giving it careful study I am in- 
clined to place it in the contradens group. 
NGpULARIA DAUTZENBERGI (Morlet). 
Shell irregularly subelliptical or subrhomboid, rather solid, 
inflated; beaks full and high, sculptured with strong, zigzag 
sculpture, which extends well over the umbonal region, grad- 
ually changing to irregular folds and nodules on the disk ; pos- 
terior ridge strong, angled, sometimes faintly double, ending 
