NODULARIA 983 
concentric bands; in the description the shell is said to be thin 
and no mention is made of the color bands. It is a shorter 
shell than ceriulea and differs in the color of its nacre. 
NODULARIA KERAUDRENI (Eydoux). 
Shell subovate, subinflated, inequilateral; beaks rather full; 
anterior end narrowed; base line curved, full behind the mid- 
dle, curving from the swelling to the blunt posterior end; 
dorsal slope subtruncate ; posterior ridge not strongly develop- 
ed, apparently somewhat double; epidermis brownish or 
brownish-green; pseudocardinals somewhat compressed, rag- 
ged; laterals delicate, curved; anterior scars well marked, 
posterior scars shallow ; nacre yellowish-white. 
Length 41, height 22, diam. I5 mm. 
Rivers and swamps of Bengal. 
Unio keraudreni Kypoux, Guer. Mag., 1838, p. 8, pl. cxvut, 
figs. I, Ia. 
Margaron (Unio) keraudreni Lua, Syn., 1852, p. 30; 1870, p. 
46. 
Nodularia keraudrenit Simpson, Syn., 1900, p. 812. 
Nodularia cerulea var. keraudrent Preston, Rec. Ind. Mus., 
VII, 1912, p. 289. 
This shell is somewhat obovate, and the outlines are much 
less angular than they are in cerulea and other related forms. 
NopULARIA SHURTLEFFIANA (Lea). 
Shell somewhat elongated, inflated, rather solid, inequi- 
lateral ; beaks full and high, sculptured with a great number of 
fine, radiating, somewhat zigzag ridges, which extend well 
on to the disk; anterior end rounded; base line straight or 
lightly curved, rather full behind the middle; posterior ridge 
full, somewhat double, ending in a feeble biangulation at and 
below the median line; surface delicately, concentrically, sub- 
granulously ridged, and having more or less fine, subradial, 
corrugated sculpture; epidermis tawny to greenish, the green 
predominating behind, slightly rayed, and having two or 
three broad green rays on the dorsal slope; pseudocardinals 
