810 PROCEEDINGS OF THE ACADEMY OF 



this species, after a comparison with the original of the figure in Haldeman'3 

 monograph. It corresponds more nearly with this species than any other how- 

 ever, and I have yielded to the opinion of Mr. Tryon, who thinks this to be the 

 species. 



CONCHIFERA. 

 Cyrenid^e. 



Sphserinm sulcatum Lam. (Cyclas similis Say.) Wissahickon ; Delaware, 

 opposite the city, and in the ditches of League Island, where the finest speci- 

 mens are fouud. Also, more rarely, in the Schuylkill. " A very small species 

 otsphcerium is found in Tryon's pond." (Tryon.) See Hartman's Cat. Shells of 

 Chester Co. 



Pisidium abditum Say. Generally found with S. sulcatum, but more rare. 



UnIONIDjE. 



Unio c a r i o s u s Say. Most abundant about Gloucester. " Very common 

 at Bristol and Tacony, and in the canal through Smith's Island." (T.) 



U. com pi anat u s Lea. Everywhere. The best specimens are found at 

 the extremity of League Island, and in the still waters of the Schuylkill. On 

 gravelly bottoms the beaks are often very much worn. I found one specimen 

 at the lower end of Peter's Island, in the Schuylkill, with two lateral teeth in 

 each valve. " Very fine specimens at Kaighn's Point." (Tryon.) 



U. Fisherianus Lea. I discovered one specimen of this shell in the 

 Schuylkill above Girard Avenue bridge. This is the only occasion, I believe, 

 on which it has been seen so far north. 



U. heterodon Lea. Rare. Schuylkill below the Fuirmount dam, (Lea.) 

 Mr, A. J. Schafhirt found it on one occasion above the dam. " Darby Creek." 

 Lea. 



U. nasutus Say. Everywhere. The principal localities are Gloucester, 

 the Schuylkill river above the dam at Fairmount, and the extremity of League 

 Island. At the latter place the largest individuals are found, and those from 

 Gloucester sometimes exhibit the colored rays. " Little Perkiomen Creek, with 

 a dark brown epidermis and more ponderous than usual." (Tryon.) 



U. ochraceus Say. More abundant at Gloucester than elsewhere, but 

 occasionally found in the Schuylkill and Wissahickon. "There is noplace 

 where this shell attains such perfect magnificence as at League Island." Tryon. 



U. radiatus Lam. Same as the preceding species. " Very good speci- 

 mens at League Island." (Tryon.) 



U. Tappanianus Lea. Is an inhabitant of the Schuylkill River, and may 

 possibly be found near the city. 



Margaritana undulata Lea. Comparatively common in the Schuylkill 

 and Wissahickon. Occasionally met with in the Delaware. "Magnificent, 

 though rare, in the head waters of Frankford Creek, on the North Pennsylvania 

 Railroad." (T.) 



M. rugosa Say. ' Same locality." (T.) 



Ancdonta flu via ti 1 is Lea. Fine specimens occur in a dam on Mill 

 Creek, at a place called Mill Town, two miles above Frankford. Not common 

 in the Wissahickon or Schuylkill, but abundant at the extremity of League 

 Island in the ditch and in the river. Also abundant at Gloucester. "Robert's 

 Pond, 22d Ward; Wingohocking Creek and Silver Lake, near Germantown, at 

 the latter place specimens have been taken 4J inches wide." (T.) 



A. i m p 1 i c a t a Say. Gloucester, Newtown Creek and League Island. 



[Sept. 



