640 UNIO 
Margaron (Unio) geddingsianus Lea, Syu., 1852, p. 33; 1870, 
P- 53- 
Unio limatulus Conran, Pr. Ac. N. Sci. Phila., IV, 1849, p. 
164; Jl. Ac. N. Seu Phila. tf 1850; p»276; pli xxv hee @) 
Margaron (Unio) limatulus Lia, Syn., 1852, p. 32; 1870, p. 
52) 
Unio whiteianus Lea, Tr. Am. Phil. Soc., X, 1852, p. 258 pl. 
xiv, fig. 8.—Obs., V, 1852, p. 14, pl. xiv, fig. 8. 
Margaron (Unio) whiteianus Lea, Syn., 1852, p. 33; 1870, p. 
53: 
Unio vibex Conran, Pr. Ac. Phila., VI, 1853, p. 260. 
Unio similis Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 169; Jl. 
Ac. N= Sci. Phila: lV, 1858,"-p0L pl sxpe fee 7ie Obs. 
Vi, 1858sp. 01, plex the, ie 
Margaron (Unio) similis Lea, Syn., 1852, p. 52; 1870, p. 53. 
Unio protensus Lea, Pr. Ac. N. Sci. Phila., IX, 1865, p. 88; 
JL sAcON: Sei, Phila.y Vil 1866) pe-256, pl: sexx i tees 
Obs., X11. 1860; p16) pl: xxxi, fie. 70 
Margaron (Unio) protensus Lea, Syn., 1870, p. 60. 
Unio radiolus Les,-Pr: Ac. Nese. Phila; 1621871, ps 1925 9k 
Ac. N. Set. “Phila, VIL, 1874; p21, pls vi, fies 1820 bs. 
XIII, 1874, p. 25, pl. vi, fig. 18. 
Another very variable species, some specimens of which 
show an affinity for the complanatus group. Generally the 
shell is rather rhomboid, subinflated and solid. The epidermis 
is darker and the surface is more concentrically sculptured 
than in U. bucklevi. 
Unio 1nsutsus Lea. 
Shell rather small, rhomboid, subinflated to inflated, in- 
equilateral, subsolid to solid; beaks full and elevated, their 
sculpture not made out; posterior ridge well developed, single 
or double, ending behind at the base of the shell in a blunt 
point or biangulation; surface sometimes nearly smooth but 
generally with rude growth lines; epidermis dull ashy-green 
to brownish or blackish, occasionally very faintly rayed; left 
valve with two small, subcompressed or stumpy, rough pseudo- 
