836 QUADRULA 
Ouadrula metanevra var. waydu SIMPSON, Syn., 1900, p. 774. 
This form is about as well separated from typical metanevra 
as is tuberosa. ‘There are intermediates, which completely con- 
nect the variety with the species. The typical wardii is a 
trifle more elongated than the average metanevra. 
QUADRULA TUBEROSA (Lea). 
Shell irregularly subrhomboid, solid, subinflated, inequi- 
lateral ; beaks high, rather full; lunule small or almost wanting ; 
anterior end rounded; base line rounded, generally emarginate 
in front of the posterior ridge; dorsal slope truncated obliquely, 
with a sinus above the posterior ridge and an angle where the 
truncation joins the dorsal line; posterior ridge elevated, 
rounded. with a shallow radial depression in front of it and 
a deeper one behind it; surface, except the anterior end, cov- 
ered with irregular, elevated tubercles ; epidermis tawny, tawny- 
greenish or brown, often having faint, triangular, green mark- 
ings, dull colored; pseudocardinals radial, marked with radial 
striz ; laterals short, that of the right valve double; beak cav- 
ities deep, compressed ; nacre white, thin and iridescent behind. 
Length 60, height 60, diam. 32 mm. 
Length 56, height 46, diam. 25 mm. 
Cumberland and Tennessee River systems. 
Type locality, Caney Fork and Cumberland rivers, Tenn. 
Unio tuberosus Lea, Pr. Am. Phil. Soc., I, 1840, p. 286; Tr. 
Am. Phil. Soc., VIII, 1842, p. 210, pl. xiv, figy 25; Obs., 
TIT, 1842, p. 48, pl. xiv, fig. 25—Cuenu, Hl. Conch., 1858, 
pl. xxvii, hies:*7, 7¢,°70: 
Margaron (Unio) tuberosus LEA, Syn., 1852, p. 22; 1870, p. 33. 
Ouadrula tuberosa SIMPSON, Syn., 1900, p. 774. 
Generally a little shorter in proportion than metanevra, not 
knobbed on the posterior ridge, smaller, less brightly painted 
and having a more decided projection of the posterior ridge. 
‘he lateral of the right valve is more completely double than 
it is in metanevra. 
