STUDIES ON NORTH 



AMERICAN POLYSTOMIDAE, 



ASPIDOGASTRIDAE, AND 



PARAMPHISTOMIDAE 



WITH ELEVEN PLATES 



BT 



HORACE WESLEY STUNKARD 



Ooatributlona from the 

 Zoological Laboratory of the ITniversity of flUnols under 

 the direction of Uenrjr B. Ward, No. 84 



