ORTMANN: monograph of the naiades of PENNSYLVANIA. 125 



South of Pennsylvania records become scarce, and aside from those given 

 by myself we have only the following: Sideling Creek, Allegany Co., Maryland 

 (Pilsbry, 1894); Richmond, Henrico Co., Virginia (Lea's U. hyalinus); and Neuse 

 River, Raleigh, Wake Co., North Carolina (Lea's U. pertemiis). 



My discovery of the presence of this species in the upper Kanawha-drainagc 

 in Virginia and West Virginia is quite astonishing and has been discussed elsewhere 

 (Ortmann, 1913a, p. 371, fig.). It should be added, that further investigations 

 have traced this species down to the Big Pool of the Kanawha (at Glen Ferris, 

 in Fayette Co., West Virginia). 



Subgenus Lasmigona Rafinesque (1831). 



Simpson, 1914, p. 488; Ortmann, 1914, p. 43. 



Type Alasmidonta costata Rafinesque. 



One species and one variety belong here. 



Key to the Forms of Lasmigona. 



Oi. Shell compressed, not subcylindrical L. (L.) costata. 



ai. Shell more swollen, and thus more nearly subcjdindrical L. (L.) costata eriganensis. 



Lasmigona (Lasmigona) costata (Rafinesque) (1820). 



Symphynota costata (Rafinesque) Simpson, 1914, p. 488. 



Plate IX, fig. 5. 

 Records from Pennsylvania: 



Harn, 1891 (western Pennsylvania). 



Stupakoff, 1894 (Allegheny Co.). 



Marshall, 1895 (Allegheny River, Warren Co.). 



Rhoads, 1899 (Ohio River, Coraopolis, Allegheny Co., and Beaver, Beaver Co.; Beaver River, Wampum, 



Lawrence Co.). 

 Ortmann, 19096, p. 196. 



Characters of the shell: SheU rather large, moderately solid. Outline sub- 

 rhomboidal or subtrapezoidal, more or less elongated. Anterior end rounded, 

 posterior obliquely truncate. Lower margin gently convex, or almost straight. 

 Upper margin straight or slightl.y curved, somewhat ascending posteriorly, and 

 forming a rounded angle with the posterior margin. Beaks not prominent, placed 

 in front of the middle of the shell. Beak-sculpture consisting of about four or 

 five bars, which are rather heavy and swollen, the first simply curved, the others 

 with a tendencj' to fall into two loops, but this is distinct only in the second and 

 third bar, where the posterior loop is angled, and the sinus is present, but not 



