ILLINOIS BIOLOGICAL MONOGRAPHS 



[226 



METHODS OF INVESTIGATION 



The methods employed in this study are those ordinarily used with 

 similar material. No special technique has been found necessary. In 

 general sections were stained in toto with Erlich's acid hematoxylin and 

 counterstained in section with alcoholic eosin. Sections were cut 10 to 

 20 micra in thickness. Frontal, sagittal, and transverse sections were 

 used. In order to obtain a clearer perception of more minute and obscured 

 parts wax reconstructions were made. These were employed particularly 

 to find the relationship and constancy of form of the female genital organs. 



MATERIAL 



The material on which this study is based is composed of various collec- 

 tions from different regions of the United States. It is limited to that 

 obtained from North American fresh water hosts and in each instance is 

 listed with the species description. However for comparison with the 

 Amerian material the following specimens were secured from the sources 

 indicated. 



EUROPEAN MATERIAL 

 From the Zoological Museum, Berlin 



Species 

 Cyclocoelum problematicum 

 Cyclocoelum problematicum 

 Cyclocoelum problem alicmn 

 Cyclocoelum ovopunctatum 

 Cyclocoelum braziiianum 

 Cyclocoelum tringae 

 Haematolrephus similis 

 Haemalolrephus similis 

 Monostomum vanelli 



From the Zoological Museum, University of Gottingen 



Cyclocoelum (Monosiomum) 



mutabile (Zed.) 

 Monostomum verrucosum 

 Monostomum attenuatum 

 Monostomum attenuatum 



284 



Gallimila chloropus 



Taken at Claustal 

 Anas bernicla 

 Mergus merganser 

 Anas fuligula 



From the Zoological JSIuseum, University of Vienna 



Monostomum mutabile Totanus flaviceps IX 552 



Taken in Brazil 



234 

 238 

 220 



Mehlis 



Mehlis 

 Mehlis 

 Mehlis 



From the Collection of Henry B. Ward, University of Illinois 



Collyriclum faba 



Passer domesticus 21 . 764 



Taken in Switzerland 



Zschokke 



Cyclocoelum leidyi 



{Monostomum mutabile 

 Zeder of Leidy) 



NORTH AMERICAN MATERIAL 

 From the Leidy Collection 



GalUnago wilsoni 160 



Leidy 



