No. 1. — Contributions to the Morpliology of the Turhellaria. 



11. 



On some Turhellaria from Illinois} By W. McM. 'Woodworth. 



The material upon which this paper is based was collected by the 

 staff of the Biological Experiment Station of the Illinois State Labora- 

 tory of Xatural History at Havana, Illinois, and came from the Uliuois 

 Eiver and the streams and lakes tributary to it.^ The material was 

 collected between the first of July and the last of October, 1894, and 

 the first of March and the last of Septeuiber, 1895. I am indebted to 

 Prof. S. A. Forbes, Director of the Illinois State Laboratory, for the 

 privilege of studying the collections, and am under obligations to Dr. 

 C. A. Kofoid, Superintendent of the Experiment Station, and to Prof. 

 Frank Smith for their patience and kindness in answering my many 

 inquiries, and for sending me living material from time to time. I must 

 thank these gentlemen also for the excellent state of preservation of all 

 the material that came into my hands. 



Although I have to report but two species that are probably new, it is 

 hoped that these pages will help to clear away some of the confusion 

 that exists in the published accounts of the North American fresh-water 

 Turhellaria. Although the figures accompanying this paper do not, with 

 two exceptions, represent new forms, they are, I believe, the first pub- 

 lished illustrations, in the natural colors of the living animals, of some 

 of our common fresh-water Turhellaria. 



I have not entered into the finer anatomy of the species to any extent, 

 as that would have been beyond the scope of the paper. L^nfortunately, 

 too, not all of the species were represented by sexually mature indi- 

 viduals, and as the characters of the sexual organs are of the highest 

 systematic importance, the unavoidable lack of data upon this subject 

 must necessarily leave my work more or less incomplete. It is to be 



^ Contributions from the Zoological Laboratory of the Museum of Comparative 

 Zoology at Harvard College, E. L. Mark, Director, No. LXXXIII. 



■'' For a description of the localities under investigation by the Experiment 

 Station, see C. A. Hart, On the Entomology of the Illinois River and adjacent 

 Waters. Bull. 111. State Lab. Nat. Hist., Vol. IV. p. 150, 1895. 



VOL. XXXI. — XO. 1. 1 



