616 UNIO 
Margarita (Unio) fulvus Lra, Syn., 1836, p. 32; 1838, p. 22. 
Margaron (Unio) fulvus Lea, Syn., 1852, p. 33; 1870, p. 54. 
The type is a voung shell and is close to U. pusillus, in fact 
Dr. Lea has one lot of shells from Rock River, North Carolina, 
labeled U. congareus that I am inclined to believe is pusillus. 
The adult shells are larger and more compressed than any I 
have seen of the latter species. 
UNIO DARIENSIS Lea. 
Shell large. subrhomboid or subtrapezoidal, convex to in- 
flated, subsolid to solid, :nequilateral ; beaks moderately full to 
inflated, somewhat elevated, their sculpture not seen; posterior 
ridge high and sharply angled, becoming double below and 
ending behind near the base in a biangulation; dorsal slope 
often wrinkled, obliquely truncated; anterior end narrowed 
and rounded; surface with rude concentric growth lines; epi- 
dermis olive-green and faintly rayed in young shells, becoming 
reddish-brown or blackish in old shells; left valve with two 
ragged, stumpy pseudocardinals and two granular laterals; 
right valve with one pseudocardinal, sometimes with a feeble 
second one above it, and one lateral; the laterals show traces 
of vertical striation; muscle scars well marked; beak cavities 
shallow to moderately deep; nacre white to purple, a little 
thicker in front. 
Length 125, height 76, diam. 42 mm. 
Length 125, height 65, diam. 33 mm. 
Length 117, height 68. diam. 48 mm. 
Southeast Georgia to north Florida. 
Type locality, New Darien, Ga. 
Unio dariensis Lea, Tr. Am. Phil. Soc., VIII, 1842, p. 246, pl. 
xxvi, fig. 61; Obs., III, 1842, p. 84, pl. xxv1, fig. 61.—CHE- 
nu, Ill. Conch., 1858, pl. xxxin, figs. 6, 6a, 6b.—SoweErsy, 
Conch. Jcon., XVI, 1868, pl. xcr, fig. 494.—Stmpson, Pr. U. 
S. Nat, Mins... 1892) px 4a ple ian, see eine oe 
Syn., 1900, p. 716. 
Marearen (Unio) dariensis Lea, Syn., 1852, p. 33; 1870, p. 54. 
