ORTMANN: monograph of the naiades of PENNSYLVANIA. 193 



Susquehanna-drainage : 

 Susquehanna River, York Haven, York Co.; Selinsgrove, Snyder Co. 

 Conewago Creek, Table Rock, Adams Co. 

 Conodoguinet Creek, Carlisle, Cumberland Co 

 Raystown Branch Juniata River, Ardenheim, Huntingdon Co.; Everett and Mount Dallas, Bedford Co.; 



Bedford, Bedford Co. (A. Koenig). 

 Driftwood Branch, Sinnemahoning Creek, Driftwood, Cameron Co. 

 Cush Cusliion Creek, Green Townsliip, Indiana Co. (D. A. Atkinson). 



Potomac-drainage: 

 Conococheague Creek, Greencastle and Scotland, Franklin Co. 

 West Branch Conococheague Creek, Mercersburg Junction, Franklin Co. 

 Great Tonoloway Creek, Thompson Township, Fulton Co. 



Localities represented in the Philadelphia Academy of Natural Sciences: 



Delaware River, Delaware Water Gap, Monroe Co. (S. N. Rhoads), and Columbia, Warren Co., New 



Jersey (S. N. Rhoads). 

 Big Neshaminy Creek, Edderton,'" Bucks Co. (H. W. Fowler). 

 Pennypack Creek, Holmesburg, Philadelphia Co. (H. W. Fowler). 

 Swamp Creek, Zieglerville, Montgomery Co. (Bayard Long). 

 Mauatawny Creek, Earlville, Berks Co. (H. A. Pilsbry). 

 Maiden Creek, Berks Co. 



Sacony Creek, Kutztown, Berks Co. (H. K. Deisher). 

 Lancaster, Lancaster Co. (J. B. Eshleman). 

 Susquehanna River, York Furnace, York Co. (W. Stone). 



Other localities represented in the Carnegie Museum: 



Stony Brook, Princeton, Mercer Co., New Jersey. 



Tioughnioga River, Cortland, Cortland Co., New York (H. H. Smith). 



Potomac River, Hancock, Washington Co., Maryland. 



Wills Creek, Ellerslie, Allegany Co., Maryland. 



South Branch Potomac River, Southbranch, Hampshire Co., West Virginia. 



Shenandoah River, Harpers Ferry, Jefferson Co., West Virginia. 



South Fork Shenandoah River, Elkton, Rockingham Co., Virginia. 



South River, Waynesboro, Augusta Co., Virginia. (Headwaters of South Fork of Shenandoah.) 



Catawba River, Bridgewater, Burke Co., North Carolina. 



Distribution and Ecology in Pennsylvania (See fig. 19) : From the published 

 records it is seen that this species belongs to the Atlantic-drainage in Pennsylvania, 

 and that it is rather evenly distributed over it, with the possible exception of 

 the larger rivers. Specimens found by myself in the Delaware and lower Susque- 

 hamia are only few. In the smaller streams this species is more abundant, and 

 locally common. This agrees well with the conditions seen in the western A. 

 marginata, and with this A. varicosa also agrees in that it is distinctly a shell which 



"•■ Probably Eddington. 



