536 UNIO 
the larger, and one lateral; beak cavities rather deep, nacre 
bluish or flesh-white, dull, a little thicker in front. 
Length 107, height 48, diam. 35 mm. 
South France. 
Unio platyrinchoideus Duruy, Cat. Ext. Gall. Test., 1849 ; Hist. 
Moll. Fr., VI, 1852, p. 649, pl. xxvii, fig. 16.—?DROUET, 
Nay. Fr., II, 1857, p. 100, pl. rx, fig. 1—Srmpson, Syn., 
1900, p. 684. 
Unio platyrhynchoideus WrSTERLUND, Faun. Pal. II, Pt. 7, 
L890; p. 121. 
Unio platyrrhynchoideus SowERBY, Conch. Icon., XVI, 1868, 
pli Exx, fies 258. 
Unio dantelis Gasstrs, Actes. Soc. Linn. de Bord., XXVI, 
1866, -p.- 132, pla, ie. 8. 
Unio lardehanus Preccutiort, Bull. Mal. It., H, 1869, p. 163, 
pl. v. 
Perfectly distinct from U. pictorum and allied species. The 
differential characters are the somewhat biangulate and drawn- 
out posterior end, the faint radial sculpture anteriorly, the 
plications on the posterior slope and the doubly-looped, fine 
beak sculpture. The shell is often almost sinuate just behind 
the middle of the base. 
UNIO ELONGATUI,US C. Pfeiffer. 
Shell elongated, thin to subsolid, subovate or subelliptical, 
subcompressed, inequilateral, beaks neither full nor high, their 
sculpture consisting of numerous fine, doubly-looped ridges, 
which are slightly nodulous at the bases of the loops; posterior 
ridge low, ending at or below the median line in a feeble bian- 
gulation; base line sometimes a little sinuate in the middle; 
anterior end rounded; surface nearly smooth; epidermis ashy- 
greenish or ashy-brownish, shaded with yellowish, subshin- 
ing, rayless; left valve with two distinct, compressed pseudo- 
cardinals and two delicate, slightly curved laterals; right valve 
