440 THE AMERICAN MIDLAND NATURALIST 
sculptured by fine concentric ridges disposed somewhat like that of 
with those from the Mississippi to find them precisely identical in 
every respect. 
Eurynia (Eurynia) recta (Lamarck).! 
(““Spectacle-Case,’”’ ‘‘Black Sand Shell.’’) 
Pl. XXVII; Figs. to0 A—D. 
1819— Umio recta Lamarck, An. Sans. Vert., VI, p. 74. 
1823— Unto praelongus Barnes, Am. Jl. Sci., 1st ser., VII, p. 261, fig. 11. 
1900b—Lampsilis rectus Simpson, Pr. U. S. Nat. Mus., XXII, pp. 
544-545. 
1912b—Eurynia (Eurynia) recta (Lam.) Ortmann, An. Car. Mus., 
VAL pa sais 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening with numerous 
papillae; anal finely crenulate; supra-anal separated from anal 
by moderate mantle connection; inner laminae of inner gills con- 
nected to visceral mass; palpi small, almost entirely free along 
their antero-posterior edges; color of soft parts grayish with its 
posterior mantle border blackish or reddish brown. 
REPRODUCTIVE STRUCTURES: — Marsupium rather kidney- 
shaped consisting of fifty large ovisacs extending below the original 
ventral line into thickened, cream-colored, cone-shaped beads 
when gravid; ova lying in irregular masses within the sacs; mantle 
edge antero-ventrad to branchial opening specialized with very 
great number of large, densely crowded papillae extending entirely 
to the center of the ventral edge; conglutinates white, glochidia 
rather medium in size, semi-elliptical, spineless, rounded ventral 
edge, hinge line undulated, measure 0.220 x 0.280 mm. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Elongate-elliptic, heavy, rather 
thick, large; female shell broader and more blunt posteriorly than 
male; no post-umbonal ridge; disk smooth; beaks large, low 
sculptured by fine concentric ridges disposed somewhat like that of 
‘This Species is the most generally distributed of the Lampsilinae. 
(See accompanying Map (Plate XXIX) for three other generally distributed 
Species; viz., Cumberlandia monodonta (Say) as representative of Margart- 
tanidae, Quadrula verrucosa (Raf.) of Unioninae and Strophitus edentulus 
(Say) of Anodontinae. 
