ORTMANN: monograph of the naiades of PENNSYLVANIA. 113 



I have located this species in the drainages of the Potomac, Rappahannock, 

 and James, in Maryland, Virginia, and eastern West Virginia, and also in a northern 

 tributary of the Potomac (Great Tonoloway Creek) in southern Pennsvlvania, 

 just North of the Mason and Dixon line. I have hunted for this species "in other 

 tributaries of the Potomac in Pennsylvania, in Antietam and Conococheague 

 Creeks, but failed to find the slightest trace of it. 



Where I collected this form, it is not at all rare. I found it either in gravel, 

 or among larger rocks, in mud-filled interstices, but generally not in strong current! 

 but in quiet coves and eddies. It also seems to prefer the smaller streams to the 

 larger rivers. 



With the exception of the Rappahannock, I never found it East of the Blue 

 Ridge, on the Piedmont Plateau or Coastal Plain, but it should be expected to be 

 more frequent there. The relation of its distribution to that of the next species 

 {E. Usherianus) should be ascertained. 



Elliptio fisherianus (Lea) (1838). 

 Unio fisher ianus Lea. Simpson, 1914, p. 692. 



Plate VIII, fig. 7. 

 Records from Pennsylvania: 



Gabb, 1S61 (SchuylkiU River, above Girard Bridge, Pliiladelphia). 



? Hartman & Michener, 1874 (White Clay Creek, Chester Co.) (see below). 



Characters of the shell: Very close to E. cupreus, and differing chiefly by some- 

 what larger size, slightly more elongated shape, and greater taper in the posterior 

 part of the shell. The greatest height of the shell is situated more anteriorly, at 

 about the beaks, and from this part the shell decreases in height to the posterior 

 end. At the same time the posterior end is more elevated, so that the posterior 

 ridge is not straight, but curves up slightly behind, and the lower margin also is 

 more curved. In all other characters this form agrees with E. cupreus. The 

 epidermis is more greenish blackish, the nacre white to purple. 



L. H. D. 



Size: 1. Kent Co., Del., Cat. No. 61.4C45 106 mm. 40 mm. 26 mm. 



2- tlo- do. 88 " 35 " 23 " 



3- do. do. 73 " 27 " 19 " 



4- do. do. 57 " 22 " 14 " 



Soft parts, glochidia, and breeding season unknown. 



Remarks: According to the material at hand, this species stands very close 

 to E. cupreus, and it possibly is only a local race (lowland form) of it. However 



