Vile A PRELIMINARY LIST OF THE, UNIONIDAY OF 
WESTERN PENNSYLVANIA, WITH NEW LOCALITIES 
FOR SPECIES FROM EASTERN PENNSYLVANIA. 
By Dr. A. E. ORTMANN. 
Several years ago, the writer, in pursuance of his studies of the fresh- 
water fauna of Pennsylvania, began to collect the freshwater shells. 
The past summer (1908) was especially favorable for collecting 
Unionidz, on account of the low stage of the rivers, and a good deal 
of work was done in this group, so that it is believed that the study of 
the mussels has progressed far enough to make it possible to give a 
general account of the Unionidz of the western half of the state. 
The region investigated covers not only the drainage of the upper 
Ohio (Monongahela and Allegheny Rivers), but also that of Lake 
Erie, and some of the tributaries of the Susquehanna. ‘The latter have 
not, however, been as thoroughly studied as the streams lying to the 
west of the divide. A number of additional localities are situated in 
southeastern Pennsylvania. 
Before we give our list of species, it seems to be weli to mention and 
discuss the previous records of the Unionidz of western Pennsylvania, 
since in many cases the nomenclature has changed, and since several 
incorrectly identified species have been listed. 
In the older publications we have only a few records from our region. 
I was only able to find the four following : 
Unio zsopus Green (Contr. Maclur. Lyc., I, 1827) = Pleurobema 
@sopus (Green). 
Described from the ‘‘ rivers in the neighborhood of Pittsburgh.’’ 
Stil present in the Ohio below, and in the Allegheny above Pittsburgh. 
Unio circulus Lea (Observ., I, 1834) = Obovaria circulus (Lea). 
Cited by Lea from the Monongahela River at Pittsburgh. The 
locality is now barren, no Unionidz being any longer present in the 
immediate vicinity of Pittsburgh. Nevertheless a few years ago this 
species was still present in the Ohio River below Pittsburgh. 
Unio coccineus Conrad (Monogr., 3, 1836, and Lea, Observ., II, 
1838) = Quadrula coccinea (Conrad). 
