UNIO 639 
their sculpture consisting of numerous ridges that run nearly 
parallel with the growth lines; posterior ridge full, rounded 
above. inclined to be narrowly double below, ending behind 
in a blunt point or faint biangulation below the median line; 
surface with irregular growth lines, nearly smooth, tawny 
and feebly rayed with green in young shells, reddish-brown 
or black, often rough and dull-colored when adult; left valve 
with two strong, ragged pseudocardinals and two curved lat- 
erals; right valve with two pseudocardinals, the upper small, 
and one lateral; anterior scars impressed; posterior scars 
shallow ; nacre varying from dull pinkish-purple to bluish or 
whitish. 
Length 96, height 55, diam. 37 mm. 
Length 68, height 39. diam. 30 mm. 
North Carolina to Florida. 
Type locality, Santee Canal, S. C. 
Umio confertus Lea; Tr. Am. Phil. Soc., V, 1834, p. 103, pl. 
xvi, fig. 47; Obs., I, p. 215, pl. xvi, fig. 47—HANLEvy, Biv. 
Shells. 1843, p. 200, pl. xx, fig. 24.—Sowrrsy, Conch. 
Icon., XVI, 1866, pl. xxxv, fig. 185—Simpson, Syn., 1900, 
aise 
Margarita (Unio) confertus Lea, Syn., 1836, p. i 
Margaron (Unio) confertus L&A, Syn., 1852, p. 33; 1870, p. 53. 
Unio lugubris Lea, Tr. Am. Phil. Soc., VI, 1838, p. 30, pl. 1x, 
nee 25 Obs., [1 .1838, p30, pls1x, fie. phe poe Biv. 
Shells, 1843, p. 206, pl. xx, fig. 9-—CHENUu, Bib. Conch., 
Tstsset. ll, 1645, p. Sappl. xv. fies. gia, 1 Conch... 1858, 
pl. xx, figs. 3, 3¢, 3b.—Sowersy, Conch. Icon., XVI, 1868, 
pl. LXxx, fig. 423-——Simrson, Pr. U. 8. Nat. Mus., XV, 
§OO2).p). 434. pl, LXVI, fig. 4.51. xVvin, fi2., 1. 
Margarita (Unio) lugubris Lea, Syn., 1836, p. 37; 1838, p. 24. 
Marzaron (Unio) lugubris Lea, Syn., 1852, p. 38; 1870, p. 53. 
Unio geddingsianus Lea, Pr. Am. Phil. Soc. I, 1840, p. 285; 
VrsAm. Phil. Soc., Vill, 1842; p-2o2, pl. x1, fig: 155, Obs. 
IIT, 1842, p. 4o, pl. x1, fig. 15. —-CHenu, II]. Conch., 1858, 
pl. xxx1, figs. 3, 3a, 3b. 
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