SIMrSONHI.LA • 1075 



SiMPSONKLLA GRACIIJS (Lea). 



Shell rather elongated, the dorsal and ventral outlines being- 

 nearly parallel, convex or subinflated, inequilateral, scarcely 

 subsolid ; bealcs only moderately full or elevated, with zig- 

 zag-radial sculpture; anterior end rounded and cut away a 

 httle below ; posterior ridge rounded or feebly double, ending 

 in a slight biangulation at and below the median line ; dorsal 

 slope obliquely subtruncate; surface with irregular growth 

 lines ; epidermis pale brownish-green and feebly rayed in the 

 younger shells, coppery-brown in old ones, scarcely shining; 

 teeth rudimentary, reduced to mere lines ; anterior scars broken 

 up ; nacre varying from bluish to purple or coppery, dull and 

 lurid ; prismatic layer wide. 



Length 85, height 40, diam. 24 mm. 



Dingle, Isle of Panay, Philippines. 

 Anodonta gracilis Lea, Pr. Zool. Soc. Lond., 1850, p. 197; Jl. 



Ac. N. Sci. Phila., IV, i860, p. 239, pi. xxxiv, fig. 119; Obs.. 



VII, i8f)0, p. 57, pi. XXXIV, fig. 119. — Clessin, Conch. Cab. 



Ano., 1873, P- 99. pi- ^xfx. figs. 3, 4. 

 Margaron (Anodonta) gracilis Lea, Syn., 1852, p. 51 ; 1870, 



p. 82. 

 DalUclla gracilis Simpson, Syn.. 1900, p. 833. 

 Siinpsonclla gracilis Ha\s, Conch. Cab., I:nio, 1912, pi. 25, 



fig- 3- 



Close to the foregoing species. It is more elongated than 

 any of them, has nearly parallel dorsal and ventral outlines, 

 is very slightly rhomboid, and has dull, lurid nacre, scarcely 

 iridescent behind. 



Simpsonella serradelli (Drouet). 



Shell ovate, inflated, thin, delicately striate with concentric 

 growth lines, shining, olivaceous ; dorsal outline slightly as- 

 cending behind ; ventral outline nearly straight ; posterior end 

 obtusely produced into a beak ; beaks rather prominent, with 

 zigzag-radial sculpture; teeth elongate, compressed, rudiment- 

 ary ; muscle impressions shallow ; nacre violaceous. 



Length 62, height 35, diam. 20 mm. 



Philippines. 



