QUADRULA 841 
Margarita (Unio) asper Lea, Syn., 1836, p. 15; 1838, p. 15. 
Margaron (Unio) asper Lma, Syn., 1852, p. 22; 1870, p. 33. 
Quadrula asper SIMPSON, Syn., 1900, p. 776. 
Quadrula aspera OrtMANN, Ann. Car. Mus., VIII, 1912, p. 
253; 
Unio turgidus Reeve, Conch. Icon., XVI, 1864, pl. 11, fig. 10. 
Unio apiculatus var. asper Payren, Conch. Sam., III, 1890, p. 
144. 
Variable in size, form, tuberculation and smoothness of epi- 
dermis, and very closely related to several other forms. Some 
specimens are almost smooth with the exception of the rows 
of strong tubercles on the median and posterior ridges, and 
approach dangerously close to forms of what I believe are 
lachrymosa. On the other hand certain shells are quite densely 
tuberculate and approach very near to apiculata. 
QUADRULA LACHRYMOSA (Lea). 
Shell subrhomboid, subinflated, solid, somewhat inequilat- 
eral; beaks high and full, their sculpture doubly looped or 
zigzagged bars, with radial threads behind them; posterior 
ridge well developed, generally somewhat double, ending at 
the base of the shell in a feeble biangulation; in front of and 
behind it there is a wide, radial depression; anterior end 
rounded; base line incurved in front of the posterior ridge; 
posterior end squarely or somewhat obliquely truncated, with a 
sinus in the middle; at the middle of the shell or a little in 
front of it there is usually a wide radial swelling ; surface gen- 
erally more or less covered with tubercles, excepting in front 
of this ridge; the sculpture on this and the posterior ridge 
often stronger than elsewhere; epidermis greenish in young 
shells, greenish-brown, brown or tawny in old ones, usually 
somewhat shining, sometimes feebly rayed; pseudocardinals 
very strong, triangular, ragged: lateral of the right valve 
somewhat double; anterior scars well impressed ; beak cavities 
moderately deep; nacre white, thinner and iridescent behind ; 
pallial line deep, roughened, remote in front. 
Length 143, height 110, diam. 63 mm. 
Length 100, height 88, diam 50 mm. 
