ORTMANN: monograph of the naiades of PENNSYLVANIA. 



15 



indistinct, even on well-preserved beaks. The fourth and fifth bars are generally 

 marked only by nodular swellings upon the posterior ridge. 



Shell rather compressed; diameter less than fifty-five percent of length. Sides 

 flattened, or even with a shallow depression in front of the posterior slope. The 

 latter separated from the sides of the shell by a distinct posterior ridge. Ventral 

 margin from straight to broadly and gently emarginate. 



Fig. 3. 

 ■ Fusconaia flava irigona. 

 • Fusconaia flava. 

 + Fusconaia flava parvula. 



Surface without sculpture. Epidermis rather light brown, or of a chestnut or 

 russet hue, raxely showing some green, with fine, indistinct, greenish w brownish 

 rays, and dark growth-rests. When older, the rays disappear, but the epidermis 

 remains rather light, and only in very old shells turns dark browm or even blackish. 



Hinge-teeth well-developed; pseudocardinals divergent, rather strong. Inter- 

 dentum present, but not very broad. Beak-cavities not very deep. Nacre white, 

 often suffused with salmon-pink. 



L. 



Size: 1. New Sheffield, Cat. No. 61.3.343 95 mm. 



2. Rosston, Cat. No. 61.2973 65 " 



* 



Soft parts and Glochidia (See Ortmann, 19116, PI. 89, fig. 2, and 1912, p. 241, 

 fig. 4). 



On May 24, 1911, in the Little Kanawha River, at Burnsville, Braxton Co., 

 West Virginia, I found among numerous gravid females with normal (red) color 



