ORTMANN: monograph of the naiades of PENNSYLVANIA. 



241 



it is also occurs in tributaries to the lake, the Maumee, Tiffin, and Sandusky Rivers 

 (See Sterki). It is found in the Ohio-drainage in Ohio (Sterki), Indiana (Call, 

 1896a, 1900). It is widely distributed in Illinois (Baker, 1906). In the Missis- 

 sippi, it ascends from Illinois and Iowa to Wisconsin (Lapham, 1860) and as far as 

 Minnesota (Grant, 1886; Holzinger, 1888). It extends down the Mississippi and 



Fig. 25. 



■ Amygdalonaias truncaia. 

 • Amygdalonaias donaciformis. 

 + Plagiola lineolata. 



to its western tributaries from Missouri (Utterback, 1916) to eastern Kansas 

 (Scammon, 1906), Arkansas (Call, 1895; Wheeler, 1918), Oklahoma (Carnegie 

 Museum), and western Louisiana (Frierson, 1899; Vaughan, 1893), and is found 

 in eastern Texas (Singley, 1893) and as far as Trinity River (Simpson). From the 

 southern tributaries of the Ohio records are scarce, but it is known from the Big 

 Sandy in Kentucky, from the Cumberland (Wilson & Clark, 1914), from Duck 

 River in Tennessee (Marshall, 1895), and from the Tennessee and its tributaries 

 in Alabama up to the Holston and Clinch in eastern Tennessee. 



Lewis (1877) cites it from the Alabama-drainage, but this has never been 

 confirmed. 



Amygdalonaias donaciformis (Lea) (1828). 

 Plagiola donaciformis (Lea) Simpson, 1914, p. 308. 



Plate XIV, figs. 8, 9. 



Records from Pennsylvania: 



Rhoads, 1899 (Ohio River, Coraopolis, Allegheny Co.). 



Characters of the shell: Shell much like that of A. truncaia, but distinguished 

 by the general shape, which is more elongated and less elevated. The posterior 

 ridge, although well marked toward the beaks, is not so sharp as in A. truncata, 

 and there is no depression in front of it. Color-markings of the epidermis of the 



