QUADRULA 855 
A fine richly-colored species, suborbicular in outline. The 
nacre and epidermis are fine, the former having comparatively 
few, irregular pustules. It is more inflated, less elongated and 
has fainter tubercles than QO. refulgens. 
QUADRULA REFULGENS (Lea). 
Shell subelliptical, subcompressed to slightly inflated, some- 
what inequilateral ; beaks elevated but not inflated, their sculp- 
ture a few coarse, nodulous ridges ; posterior ridge subangular, 
ending in a blunt point near the base of the shell; anterior 
end rounded or very little truncate above; base line curved ; 
outline of dorsal slope curved, often raised to an angle in the 
middle; on the disk there is a wide band extending from the 
umbonal region to the base that is covered with large, low, 
rather even nodules; dorsal slope somewhat nodulously wrink- 
led; anterior end without nodules ; epidermis reddish-chestnut, 
subshining; pseudocardinals triangular, ragged, two in the 
left valve and three in the right; lateral in right valve single 
or double; beak cavities deep, compressed ; muscle scars small, 
impressed; nacre purple or violet, iridescent behind. 
Length 48, height 38, diam. 23 mm. 
Length 50, height 40, diam. 28 mm. 
Mississippi and probably Alabama. 
Type locality, Oktibbiha River, Lauderdale Co., Miss. 
Unio refulgens Lea, Pr. Ac. N. Sci. Phila., XII, 1868, p. 145; 
jim AceN Sci. Phila, Vi, 1860;p.. 317; pl. L1, fig. 130; Obs., 
ME 1860, p: 77, pl. L1, fig. 130. 
Margaron (Unio) refulgens Lea, Syn., 1870, p. 34. 
Quadrula refulgens StmPson, Syn., 1900, p. 782. 
Unio pustulosus Cau, (part), Tr. Ac. Soc. St. Louis, VII, 
FSO5, ps 42, pl xv, hese aoe 
Typically quite distinct from spherica, but there are exam- 
ples that almost connect the two. Generally the pustules on 
this species are large, rather regular and evenly spaced, and 
they occupy a wide band in front of the posterior ridge, run- 
ning vertically, while in spherica they are smaller and less reg- 
ularly disposed. The shell is more elliptical and compressed 
than spherica. 
