PLATE 1 
EXPLANATION OF FIGURES 
1 Gravid female of Ptychobranchus phaseolus. X f 
2 Gravid female of Lampsilis subrostratus. Natural size. 
3 Gravid female of Obliquaria reflexa. Natural size. 
4 Gravid female of Quadrula ebena. X h 
5 Gravid female of Lampsilis rectus. X h 
6 Gravid female of Symphynota co nplanata. X h. 
