GIBBOSULA 941 
Three shells of this remarkable form are before me and 
they vary a good deal in dimensions, but agree very well in 
the essential characters. ‘The one whose measurements are 
first given is probably hardly adult and is elegantly painted ; 
the other two are older and not so bright. I know nothing 
whatever of the anatomy of this species and it is only placed 
near Quadrula provisionally. Its form and the deep beak 
cavities would seem to ally it to that genus. 
SCHISTODESMUS SPINOSUS Simpson. 
Shell somewhat triangular, inequilateral, subinflated or in- 
flated, moderately solid; beaks rather full and high; posterior 
ridge apparently well developed, angular, ending in a blunt 
point not far above the base of the shell; anterior end obliquely 
truncate above, rounded below; base line rounded; outline 
of dorsal slope curved; surface apparently sculptured with a 
few, widely spaced, concentric furrows, having wide, flat 
ridges between them, having on the posterior ridge one or 
more, well-developed, short spines; epidermis probably bright, 
with narrow, scattered, broken rays; right valve having the 
hinge plate cut off at the beak, its lateral somewhat double. 
Length 35, height 30, diam. 20 mm. 
China. 
Unio vestitus HeupDE, var. B, Conch. Fluv. Nank., VIII, 1883, 
PLL foe TDS. 
Shistodesmus spinosus SIMPSON, Syn., 1900, p. 804. 
Schistodesmus spmosus Haas, Conch. Cab., Unio, 1912, pl. 31, 
fig. 5. 
Heude makes this a variety of his Unio vestitus, but it seems 
to me to be totally different and closely related to, if not a 
variety of, lampreyanus. He gives no separate description, so 
I am in the dark regarding several important characters. The 
ridges are wider than in lampreyanus and the latter has no 
spines. 
Genus GIBBOSULA Simpson, 1900. 
Gibbosula SIMPSON, Syn., 1900, p. 804. 
Shell very solid, inequilateral, triangular, elliptical, arcuate, 
pointed behind, with a low, well-marked posterior ridge; beaks 
