ABSTRACT 



A key is presented for the identification of the species of North 

 American freshwater triclads or planarians known at present. 

 Introductory chapters deal with the collecting, culturing, pres- 

 ervation, study, and general organization and life cycle of 

 planarians. The key is followed by a listing of the species and 

 subspecies, giving their distinguishing characteristics, ecological 

 requirements, and geographic ranges. Illustrations depict the 

 external appearance and diagrams of the reproductive organs of the 

 individual taxa. The principal literature for each species is 

 indicated and listed in the appended bibliography of 65 items. An 

 index of the generic and specific names and synonyms concludes the 

 report. One new subspecies, Polyaetis aovonata brevipen-is , is es- 

 tablished for L. H. Hyman's Polyaetis ooronata. 



This report was submitted in fulfillment of Project #18050ELD, 

 Contract #14-12-894 under the sponsorship of the Environmental 

 Protection Agency, 



