UNIO 5am 
the lower higher; right valve with two compressed pseudocar- 
dinals, the upper small, and one high lateral; nacre bluish- 
white, usually rather dull, thickened a little in front. 
Length 68, height 26, diam. 18 mm. 
Central and southwestern Europe. 
Unio platyrhynchus RossMASSLER, Icon., LI, 1835, p. 22, pl. 1x, 
fig. 130; V, 1837, p. 20, pl. xxiv, fig. 338.—HAanL_Lgy, Biv. 
Shells, 1843, p. 205, pl. xx111, fig. 53.—Kuster, Conch. Cab. 
Unio, 1854, p. 77, pls. x1x, xx.—SowersBy, Conch. Icon. 
XVI, 1856, pl. xxx, fig. 154.—Srmpson, Syn., 1900, p. 683. 
Margarita (Unio) platyrhynchus Lea, Syn., 1836, p. 35; 1838, 
p. 24. 
Margaron (Unio) platyrhynchus Lea, Syn., 1852, p. 36; 1870, 
p. 58. 
Umo fiscallianus Kieciacu, Atti. Soc. Ital., XV, 1872, p. 92. 
—PFEIFFER and Koper, Mal. Blatt., XX, 1873, p. 92, fig. 
Unio limosus Kopett, Icon., new ser., VI, 1893, p. 44, pl. 
CLVII, figs. 1024-1027. 
A most distinct and peculiar species, always distinguishable 
when adult by the curious, compressed beak at the hinder base.. 
Generally the surface is roughened and dull, though the earlier 
growth is bright and smooth, and until it is near maturity the 
shell is almost exactly like a young, delicate pictorum. 
UNIO PLATYRINCHOIDEUS Dupuy. 
Shell elongated, subinflated, somewhat ovate or rhomboid, 
inequilateral, subsolid; beaks full, rather high, their sculpture 
consisting of fine, doubly-looped, nodulous ridges; posterior 
ridge high, angled, somewhat double below ; anterior end sub- 
truncate, angled above; posterior slope obliquely truncated, 
plicately corrugated ; surface otherwise nearly smooth, having 
faint growth lines and obsolete radial sculpture anteriorly ; 
epidermis shining, olive-green to burnt-brown, showing the 
dark rest periods; left valve with two compressed pseudocar- 
dinals, which are almost united into one, and two curved, deli- 
cate laterals; right valve with two pseudocardinals, the lower 
