568 UNIO 
almost squarely truncated; base line nearly straight; anterior 
end narrowed and rounded; surface with strong, uneven 
incremental striz; epidermis ashy-green, ashy or reddish- 
brown, dull; pseudocardinals compressed; laterals delicate ; 
beak cavities not deep; muscle scars shallow; nacre flesh-col- 
ored, sometimes blue-tinted, a little thicker in front. 
Length 56, height 30, diam. 18 mm. 
Southern Europe. 
Unio carneus Kuster, Conch. Cab. Unio, 1854, p. 103, pl. 
XXVIII, figs. 1, 2—SimMpson, Syn., 1900, p. 696. 
Unio gontierti BourcuIGNAT, Rev. et Mag., IX, 1857, p. 16, pl. 
Iv, figs. 1-4. 
Margaron (Unio) gontieri Lea, Syn., 1870, p. 44. 
Unio penchinatianus Bourcuicnat, Moll. Peu. Con., 1863, p. 
A4, pl: xxv. Rev. et Mac. XS 1865p, 342, pean — 
Koper, leon: 1V, 1876,-p. 66, pl: cx nev rrss. 
Close to forms of U. batavus and bearing about the same 
relation to it that elongatulus does to pictorum. It is less in- 
flated, is thinner and rougher than batavus and is more decid- 
edly widened and biangulate behind. 
Unio BAtavus (Maton and Rackett). 
Shell long elliptical, subrhomboid or when old slightly arcu- 
ate. subsolid to solid, convex to subinflated, inequilateral ; 
beaks slightly elevated above the dorsal line and but moderate- 
ly inflated, sculptured with numerous rather fine, corrugated, 
broken ridges; sometimes these ridges are somewhat doubly 
looped and subnodulous; posterior ridge low and rounded; 
surface with fine or uneven incremental lines, sometimes nearly 
smooth ; epidermis vellowish-green or greenish-vellow, tawny. 
olive, brownish or almost black, often rayed, especially in the 
lighter colored examples; left valve with two small, subcom- 
pressed or stumpy pseudocardinals and two straight or faintly 
curved laterals; right valve generally having two pseudo- 
cardinals, the upper small, sometimes wanting, and one lat- 
eral; beak cavities not deep; muscle scars rounded, the anterior 
