256 Trans. Acad. Sci. of St. Lowis. 
variety which this species exhibit in the pustulosity of its 
shell, the extremes being perfectly smooth and densely ee 
lose. Distortions rare. 
QUADRULA PUSTULATA Lea. 
Not common. 25 per cent contained pearly secretions. 
QUADRULA TRIGONA Lea. 
Very common. The nacre of the specimens from this lo- 
cality varies from white to salmon-pink. Pearly secretions 
are common, at least 70 per cent containing abnormal pearly 
matter. One specimen contained an erect, sharp piece of 
pearly matter extending across the middle of the anterior 
muscle scar. 
QUADRULA OBLIQUA Lamarck. 
Very rare. Only one specimen secured. 
QUADRULA EBENA Lea. 
Very common. This is the pearl shell par excellence to 
the mussel fishermen. Of those secured, 25 per cent con- 
tained pearly secretions and one specimen had the left valve 
badly diseased. Distortions rare. 
QUADRULA GRANIFERA Lea. 
Apparently rare. Only two specimens were obtained. 
The nacre is of a peculiar deep copper color. 
Class GASTROPODA. 
Family VIVIPARIDAE. 
VIVIPARA INTERTEXTA Say. 
Common in the Mississippi River. 
VIVIPARA SUBPURPUREA Say. 
Common. 
CAMPELOMA INTEGRUM De Kay. 
Common. 
