804 PROCEEDINGS OF THE NATIONAL MUSEUM. 



beautiful, granularly striate callus is developed behind the laterals; 

 nacre finely, often bifurcately radiate striate outside the parallel line. 

 Animal unknown. 



t SHISTODESMUS LAMPREYANUS Baird and Adams. 



* Unio(Dysnomia)lampreyanu8, BAiRi>andAnAMS,Proc.Zool.Soc. Lond., 1867, p. 491, 



pi. xxvi, figs. 2, 2a. * SOWERBY, Conch. Icon., XVI, 1868, pi. LXXXVII, fig. 

 469.* HKUDE, Conch. Fluv. Nank., VII, 1883, pi. LIX, figs. 114, 114o, 114b. 

 -P.ETKL, Conch. Sam., Ill, 1890, p. 156: 

 Maryaron ( Unlo) lampreyanns LEA, Syn., 1870, p. 30. 



SHISTODESMUS SPINOSUS Simpson. 



1'nio restitus var. ft, HEUDK, Conch. Flnv. Xank., VIII, 1883, pi. LIX, fig. 115.' 

 Genus GIBBOSULA Simpson, 19OO. 

 (Type, Mya crassa Wood.) 



Shell very solid, inequilateral, triangular-elliptical, arcuate, pointed 

 behind, with a low, well-marked posterior ridge; beaks rather high; 

 beak sculpture not seen; posterior two-thirds of the shell covered with 

 somewhat radiating corrugations and nodules; posterior slope having 

 strong subradial folds; epidermis dark ; hinge plate very wide; pseudo- 

 cardinals not large, stumpy, rough; laterals very heavy, club shaped; 

 beak cavities enormously deep and compressed; anterior cicatrices 

 rather shallow, rough in the bottom; posterior cicatrices deep and dis- 

 tinct; a strong rib runs from the front part of the beak cavity toward 

 the posterior base; nacre whitish. 



Animal unknown. 



t GIBBOSULA CRASSA Wood. 



* Mya crassa WOOD, Gen. Conch., 1815, p. 106, pis. xx, xxi ; 2 * Ind. Test., 1825, p. 12, 



pi. n, fig. 28ft; *Ind. Test. Rev., 1856, p. 16, pi. n, fig. 28. 



* Mya ponderosa DILLWYN, Dill. Cat., I, 1817, p. 51. 



* Margarita f'nio ponderosus LEA, Syii., 1836, p. 14; 1838, p. 14. 



* Unio ponderosus HANLEY, Test. Moll., 1842, p. 177; *Biv. Shells, 1843, p. 177. 



* CATLOW and REEVE, Conch. Noni., 1845, p. 63. * H. and A. Adams, Gen. 

 Rec. Moll., II, 1857, p. 497. 

 " Maryaron ( Unio) ponderosus LEA, Syii., 1852, p. 21; 1870, p. 32. 



China. 



Genus CUNEOPSIS Simpson, 19OO. 

 (Type, Unio celtiformis Heude.) 



Shell solid, elongated, wide and truncate or rounded in front, taper- 

 ing to a point behind; often twisted on its axis and curved to the right 



1 Heude made this a variety of his Unio vestitus (which I have placed in Quadmla. 

 I aui satisfied that this is a Shistodesmns and distinct from lampreyanus, as it seems 

 to have spines instead of knobs. His name vestitus is preoccupied in Unio by Lea.) 



-The name crassus had been previously applied to a Unio by Retzius, but as 

 Wood's species was never placed in Unio under the specific name craasi/s, his name 

 may be used. 



