858 QUADRULA 
There are six shells bearing the name Unio nodiferus Con- 
rad in the Philadelphia Academy of Natural Sciences. Part 
of them are the same as figured in the Journal, and the rest 
are probably mortomi. 
QUADRULA CAHABENSIS (Lea). 
Shell subquadrate, compressed or subcompressed, slightly 
inequilateral, moderately solid; beaks elevated and full; an- 
terior end rounded; base nearly straight ; posterior end oblique- 
ly truncated, the upper part overhanging ; posterior ridge low, 
widely rounded; surface thickly covered, except the upper an- 
terior portion, with strong, wart-like tubercles, which on the 
posterior slope are sometimes elongated; epidermis tawny to 
brownish, showing the dark growth lines; pseudocardinals 
radial, roughened; lateral in right valve single or double ; beak 
cavities deep, compressed; anterior scars small; nacre flesh- 
color or salmon-tinted, brilliant, thinner and iridescent behind. 
Length 46, height 37, diam. 18 mm. 
Cahawba River, Alabama. 
Type locality, Cahawba River, Shelby Co., Ala. 
Unio cahabensis Lea, Pr. Ac. N. Sci. Phila., XXIII, 1871, p. 
190 3 JL Ac! N Set Fanila., “Viti 1874 ool oleate leemaletes 
Ob; SGIIL 1874p: Zu pla ve ere 
Quadrula cahabensis SIMPSON, Syn., 1900, p. 782. 
I have seen larger shells than the type (whose measure- 
ments I have given) in the collection of T. H. Aldrich of Bir- 
mingham, Alabama. ‘Typically it is quite distinct from Q. 
vallata, being more compressed, more quadrate and having 
brighter epidermis and nacre, but I should not be surprised 
if an abundance of material would demonstrate that the two 
run together. 
QUADRULA VALLATA (Lea). 
Shell subquadrate, convex or subinflated, solid, subequilat- 
eral; beaks neither very full nor high; anterior end slopingly 
truncate above, rounded below; base line nearly or quite 
~ straight ; posterior end somewhat obliquely truncated, the up- 
