UNIO 561 
Kobelt supposed this to be the Unio hueti of Bourguignat 
and figured and described it for that species. It is however, 
quite distinct from that and is apparently undescribed. It is 
greatly inflated, more so than any member of the group that 
I am acquainted with, is solid, and apparently has strong, 
concentric sculpture. It is rather remarkable in having the 
front half rayed and the hinder half rayless. 
UNIO FERUSSACIANUS Lea. 
Shell irregularly subelliptical or subtrapezoid, subsolid, cou- 
vex, somewhat inequilateral; beaks somewhat elevated and 
full, pointed, sculptured with a large number of corrugated, 
more or less broken, ridges, which show a tendency to be 
doubly looped, the sculpture extending well out on to the disk ; 
posterior ridge scarcely developed; dorsal line arched, ending 
behind in a feeble angle at the subtruncation of the posterior 
slope; base line nearly straight; anterior end evenly rounded 
and a little narrowed; surface finely concentrically striate, 
greenish-yellow, feebly rayed behind and showing dark brown 
rest periods: left valve with two high, compressed, sharp pseu- 
docardinals and two straight laterals; left valve with a high, 
compressed lower pseudocardinal and a faint upper one with 
one somewhat double lateral; beak cavities moderately deep; 
nacre bluish-white, scarcely thicker above. 
Length 48, height 31, diam. 19 mm. 
Bagdad. 
Unio ferussacianus Lea, Jl. Acad. Nat. Sci. Phila., VI, 1868, 
p- 255. Footnote to description of U. emesaensis—L*A, 
Obs. XII, 1869, p. 15. Footnote——Simpson, Syn., 1900, p. 
604. 
Margaron (Unio) ferussacianus Lea, Syn., 1870, p. 46. 
This may be only a variety of U. durieui, but it is shorter, 
solider and a little more inflated than that species. The great- 
est inflation is at the middle of the shell and from this point 
it is wedge-shaped in front and behind while duriew is almost 
evenly convex. 
