I074 SIMPSONEI.I.A 



Close to crepera, but more decidedly rhomboid, the anterior 

 base of some specimens being somewhat cut away. The 

 posterior ridge is quite high, so much so that there is a faint 

 radial depression in front of it, while that of crepera is rather 

 low. The point of greatest diameter is situated nearer the 

 posterior end than in crepera. 



SiMPSONEI.IyA SUBCRASSA (Lea). 



Shell subrhomboid. subsolid. slightly inflated, inequilateral ; 

 beaks rather full and high, with zigzag-radial sculpture ; an- 

 terior part of the shell scarcely narrowed ; anterior end round- 

 ed, cut away a little below ; base line straight or incurved ; dor- 

 sal outline lightly curved ; dorsal slope obliquely truncate 

 above; posterior ridge full, feebly angled, ending in a blunt 

 point below the median line ; surface with fine, irregular 

 growth lines on the disk, these become stronger at the ends 

 of the shell ; epidermis pale greenish-brown with faint rays, 

 often having a grayish, silky surface when not worn ; teeth al- 

 most wholly wanting, linear ; nacre bluish, salmon-tinted or 

 purplish. 



Length 75, height 40, diam. 29 mm. 



Luzon Island. 

 Anodonta subcrassa Lea, Pr. Zool. Soc. Lond.. 1850, p. 198; 



Jl. Ac. N. vSci. Phila., IV, T859, p. 236. pi. xxxiii, fig. 115; 



Obs., Vll, i860, p. 54, pi. XXXIII, fig. 115. — Musgrave, 



Phot. Conch., 1863, pl- i- ^S- 3- — Clessin, Conch. Cab. Ano., 



1873, p. 98, pi. XXXI, figs. I, 2. 

 Margaron f Anodonta) subcrassa Lija, Svn.. i8s2, p. 51 ; 1870, 



p. 81. 

 Anodon subcrassa Sowerp-y, Conch. Icon., XA^II, 1867, pi. 



XTii, fig. 42. 

 Dalliella subcrassa Simpson, Syn., 1900, p. 833. 

 SinipsoneUa subcrassa Haas, Conch. Cab., Unio. 1912, pi. 25. 



fig. 2. 



More solid than the allied species and somewhat more in- 

 flated. The epidermis in fresh specimens is wholly or partly 

 covered with a peculiar grayish, silky sort of bloom, which 

 Avears off to some extent after thev are handled. 



