ORTMANN: monograph of the naiades of PENNSYLVANIA. 165 



very wide range, but it should be qualified somewhat. It is actually found over 

 large parts of the Mississippi-drainage, but records are missing from the tributaries 

 South of the Ohio. In the Cumberland-drainage, it is only found in ponds near 

 Clarksville, Montgomerj^ Co., Tennessee (Wilson & Clark, 1914); and in the 

 Tennessee-drainage it goes up to northern Alabama, but seems to be missing in 

 East Tennessee. Northward it passes into the lake-drainage in Wisconsin (IVIil- 

 waukee, Lapham, 1860), Illinois (Baker, 1906), Michigan (Walker, 1898), Ohio 

 (Sterki, 1907rt; Walker, 1913), and advances northeastwards to northwestern 

 Pennsylvania and western New York, reaching, by way of the Erie Canal, Herkimer 

 Co., New York (Lewis, 1860; Marshall, 1895). In the upper Mississippi, it 

 ascends to southeastern Minnesota (Grant, 1886; Holzinger, 1888). 



Westward it occurs in the tributaries of the Mississippi in Kansas (Scammon, 

 1906), Arkansas, Oklahoma, and northwestern Louisiana (Vaughan, 1893; Frier- 

 son, 1899). It is frequent in the streams flowing into the Gulf in Texas (Singley, 

 1893), reaching Matamoras in Mexico, according to Simpson. In addition it is 

 known from the Alabama-drainage, going thence into Georgia and the Carohnas. 

 This section of the range is represented in the Carnegie Museum by specimens 

 from Alabama, Georgia, and North Carolina, and is probably connected westward 

 with the localities in Louisiana. 



Genus Anodontoides Simpson (1898). 

 Ortmann, 1912, p. 293; Simpson, 1914, p. 466. 



Type Anodonta ferussaciana Lea. 



Only one species is known, which, however, has several varieties, one of which 

 is found in Pennsylvania. 



Key to the Forms of Anodontoides. 



tti. Shell compressed, and less elongated .4. fencssacianus. 



a 2. Shell more swollen, more elongated, thus approaching the subcylindrical shape. 



A. ferussacianus buchanensis. 



Anodontoides ferussacianus (Lea) (1834). 

 Anodo7itoides ferussacianus (Lea) Simpson, 1914, p. 467. 



Plate XI, fig. 5. 

 Records from Pennsylvania: 



Ortmann, 19096, p. 195. 



Characters of the shell: Shell small to medium in size, thin. Outline sub- 

 eUiptical or subovate, moderately elongate, rounded anteriorly as well as posteriori}', 



