78 



Bryant Walker 

 Subgenus MICROMYA Agassiz, 1852. 



Shell small or of medium size, suboval or subelliptical, not very long 

 and not much pointed behind; beak sculpture distinctly double-looped, but 

 often obsolete, the posterior loop often showing a tendency to be open. 



Fig. 212 



mp PP 



Fig. 213 



Inner edge of the mantle of the female in front of the branchial open- 

 ing with a shorter or longer row of rather irregular, larger and smaller 

 papillae, reaching not quite to the middle of the lower margin. 



Type: Unio fabalis Lea, fig. 212. Animal, £. iris (Lea), fig. 213. 

 Genus LAMPSILIS Rafinesque, 1820. 



Fig. 214 



Shell oval to elliptical, smooth or shghtly, concentrically sculptured, us- 

 ually without a posterior ridge; epidermis generally smooth and shining, 

 often rayed; beak sculpture, consisting of double-looped, parallel ridges, 

 sometimes the posterior loop open behind or the sculpture is obsolete ; hinge 



