152 MEMOIRS OF THE CARNEGIE MUSEUM. 



The form found in this lake, represented in the Carnegie Museum by numerous 

 specimens, is a small race of A. grandis, possibly to be placed with benedidensis, 

 but not with footiana. 



A. grandis footiana belongs preeminently to the St. Lawrence system, and 

 has a wide range in it. It crosses over into the Mississippi as well as the Hudson 

 Bay drainages, but only very slightl}', and in the former it intergrades with A. 

 grandis. 



Anodonta cataracta Say (1817)."^ 

 Anodonta cataracta Say. Simpson, 1914, p. 386. 



PlateX, fig. 5; Plate XI, fig. 1. 



Records from Pennsylvania: 



Haldeman, 1844 (Lancaster Co.). 



Gabb, 1861 (Mill Creek, Milltown; Wissahickon Creek and Schuylkill River, Philadelphia, Germantown 

 and League Lsland, Philadelphia Co.). 



Lea, 1867 (Schuylkill, Delaware River, and League Island, Philadelphia) {tryoni). 



Bruckhart, 1S69 (Lancaster Co.). 



Hartman & Michener, 1874 (Schuylkill River, Chester Co.). 



Pilsbry, 1894 (York Furnace, York Co.)."^ 



Schick, 1895 (Delaware and Schujdkill Rivers, Fairmont Park, League Island, Philadelphia; German- 

 town, and Canal at Manayunk, Philadelphia Co.; Munckinipattus Creek, Glenolden, Delaware 

 Co.). 



Marshall, 1895 (Tributaries of Genesee River, Potter Co.;'" Juniata River). 



Ortmann, 1909/*, p. 205. 



Caffrey, 1911 (Lehigh Canal and ponds, Bethlehem, Northampton Co.). 



Characters of the shell: This species is very close to A. grandis, and the only 

 reliable difference is in the beak-sculpture, and even this is a difference rather of 

 degree of development than of type. The general character of the beak-sculpture 

 is the same in both species (double-looped), but while in A. grandis the two loops 

 are sharply separated by a sinus, which is generally depressed (notch-hke), and 

 while the posterior loop is tuberculiform, in A. cataracta the bars of the beak- 

 sculpture, which are also slightly more numerous (five to seven) are uniform in 

 elevation, and in the sinus they are not appreciably lower than in front and behind 

 of it, so that no tubercles are formed. These differences have properly been pointed 

 out by Marshall (1890, p. 188, 189). In the light of my material I have only to 

 add, that the first two bars are simpl_y concentric, and that those following are 



'" Not 1816, see p. 9. 



"■- Pilsbry's (p. 30) " A. siihcylindrica Lea " is this species. I have seen the specimens so labeled 

 in the Philadelphia Academy of Natural Sciences. 

 "' This locahty should be confirmed. 



