QUADRULA — 897 
double; beak cavities moderately deep, compressed; muscle 
scars small, impressed; nacre rich pink, thinner and iridescent 
behind. 
length so, height 45, diam. 33 mm. 
lLength 50, height 42, diam. 26 mm. 
Arkansas; Louisiana; Sabine River, Texas. 
‘Type locality, Little Red River, Ark. 
Unio cuneus Conrav, Monog., XII, 1840, p. 105, pl. Lvri, fig. 
Pp 
Quadrula cuneus SIMPSON, Syn., 1900, p. 792. 
There are a number of Conrad’s species, which according 
to his figures and descriptions differ from anything I have 
ever been able to examine, even though in several cases I have 
seen material from the type localities, and this is one of them. 
Conrad’s Unio cuneus was obtained from the Little Red River, 
Arkansas, and I have before me specimens from that same 
stream, which are thinner, smoother, less inflated and not 
so decidedly wedge-shaped as his description and figures show. 
Yet I think they must be cuneus. I have seen no shells which 
agree any more closely with his Unio productus, U. contrarius, 
U. furvus, U. maculatus, U. perovatus, Alasmodonta radiata, 
Anodonta subvexa, A. teres, etc., though I have seen examples 
of what are probably a considerable number of these species. 
Conrad was an excellent naturalist, but was careless and in a 
number of cases his descriptions are considerably at variance 
with his figures, and his localities are apparently wrong. 
QuADRULA EBENUS (Lea). 
Shell subquadrate or subelliptical, inflated, solid, very inequi- 
lateral; beaks exceedingly high, full, turned inward and for- 
ward over a lunule, their sculpture a few rather feeble corru- 
gations ; anterior end squarely or obliquely truncate above un- 
der the sometimes overhanging beaks, rounded below; base 
rounded, straight or incurved in old shells; outline of dorsal 
slope a full curve: posterior ridge rather low, often somewhat 
double, curved; surface with low, irregular, concentric ridges ; 
epidermis tawny-brown, reddish-brown or blackish, usually 
