1 132 rA.RRi:VSIA 



ter of the disk, the whole sliell frequently corrugate sculp- 

 tured ; epidermis greenish, often slightly rayed ; teeth solid, 

 much like those of typical Parrcysia; nacre white or hluish, 

 sometimes microscopically, granularly radiate outside the pal- 

 lial line ; beak cavaties not deep ; anterior scars distinct. 

 Animnl unknown. 



Parrkysia nvassaknsis (Lea). 



Shell rhomboid, solid, subinflated, inequilateral ; beaks high, 

 full, with strong, zigzag sculpture, which extends over the disk 

 nearly or cpiite to its outer edge, becoming subnodulous in 

 ])laces. plicate on the dorsal slope; there being also a pattern 

 of irregular, concentric ridges and sometimes feeble radiat- 

 ing furrows ; anterior end rounded ; base straight or lightly 

 curved ; hinge line lightly arched, angled where, it joins the 

 ol)liquely subtruncate dorsal slope ; posterior ridge high, sub- 

 angular; c])idermis ashy to greenish, sometimes feebly banded 

 and rayed, subshining ; hinge solid ; pseudocardinals much 

 split up; laterals more or less double in each valve; anterior 

 scars impressed ; nacre whitish or flesh-colored. 



Length 33, height 23, diam. 15 mm. 



Length 30, height 22.5, diam. 15 mm. 



Lake Nyassa, Central Africa. 

 Uyiio nyassacnsis Lea, Pr. Ac. N. Sci. Phila., VIH, 1864, P- 



108; Jl. Ac. N. Sci. Phila., VL 1866, p. 33, pi. xii. fig. 32; 



Obs., XI, 1867, p. 2,7^ pl- XII, fig. 32. — Smith, Pr. Zool. Soc. 



Lond., i88r, p. 298, pl. xxxiv, fig. 34. 

 Margamn fUnio) nyassacnsis Lea, Syn.. 1870, p. 30. 

 Parreysia nyassaensis Simpson, Syn., 1900, p. 848. 

 Unio nyasscp Sowkrhy, Conch. Icon., XVI, 1868, pl. xu. figs. 



224, 224a, 224^. 

 Unio nyassaniis P)OiTRGUiCNA'r, Bull. Soc. ^lal. Fr., \^L 1889, 



p. 38'. 

 Unio hcniiosits Rourguicnat, Bull. Soc. Mai. Fr., VI, 1889, 



p. 38. 



The above measurements are first from the type and the 

 second from a shell belouirins' to the Morelet collection. 



