‘THe NAUTILUS. 
VoL. XII. APRIL, 1899. No. 12. 
ON A RECENT COLLECTION OF PENNSYLVANIAN MOLLUSKS FROM THE 
OHIO RIVER SYSTEM BELOW PITTSBURG. 
BY SAMUEL N. RHOADS. 
Owing to the steady extermination of the molluscan life of the Ohio 
river in western Pennsylvania, due to the pollution and damming of 
the waters of that river and of the Monongahela, and to a smaller extent 
of the Allegheny river, any information relating to the species still 
existing in these: waters must be quickly put on record to be pre- 
served. It is the aim of this paper to give a list, briefly annotated, 
of the fresh water species recently collected by the writer in the vicin- 
ity of Pittsburg. While the time devoted to this collection was lim- 
ited to less than a week’s work, and the number of species taken do 
not duplicate all those hitherto secured by local collectors in that re- 
gion, it seems desirable to publish, if only to inspire others more fa- 
vorably situated than myself to record their knowledge in this line be- 
fore it is too late. Indeed, it is remarkable, when we consider the 
amount of molluscan research carried on by the conchologists of Penn- 
sylvania that as yet nothing in the nature of a faunal list of the aquatic 
mollusca of western Pennsylvania has ‘yet appeared.* Before giving 
the list it is proper to enumerate some of the agencies which are surely 
accomplishing the extinction of so much of the fluviatile life of the 
Ohio river and its tributaries. Above the city of Pittsburg the Mo- 
nongahela is bordered for the greater part of its navigable length with 
factories, furnaces, refineries, mines, and oil and gas wells, whose 
refuse products are continually draining into the river. The sewage 
of the towns on this river is also a factor in its pollution. Great as 
this pollution may appear, it is not likely that it would cause the death 
*Some Unionide from the Allegheny river in Warren county, Pennsylva- 
nia, were listed by W. B. Marshallin Bulletin of the New York State Museum, 
Voll, but as no localities are given in the list it is impossible to determine 
whatspecies were taken in Pennsylvania and what in New York. 
