225] NORTH AMERICAN MONOSTOMES 



INTRODUCTION 



The study of the Monostomata was undertaken four years ago following 

 the suggestion of Professor Henry B. Ward, who expressed the need for a 

 thorough study of the group. A preliminary survey of the available mate- 

 rial served to convince me that a more complete and comparative study 

 of the group was desirable and that such a study would prove of value to 

 helminthologists. This study seemed more desirable since but two com- 

 parative studies of the group had been made in the last twenty-five years. 

 The first of these was that of Stossich (1902) which is based wholly on 

 European material; the second that of Kossack (1911) is based largely on 

 the same material. The fact that very little had been done on this group 

 in America and that no comparative study of the American fauna had been 

 undertaken furnished further incentive for this work. 



The writer undertook an investigation of the group which should be 

 comprehensive in scope and at the same time comparative. For this pur- 

 pose he had free and unlimited use of the large personal collections of 

 Professor Ward secured thru extensive field work as well as obtained by 

 exchange. These had been augmented, with a view to getting a complete 

 series, by loans of material from European and American investigators. 

 Unfortunately specimens of certain originals could not be secured either 

 because they had been lost or because they could not be removed from the 

 collections. 



Thanks are due to the following investigators who at the request of 

 Professor Ward kindly sent material from valuable collections for study 

 and comparison; Professor Anton Collin, University of Berlin; Professor 

 Theodor Pintner, University of Vienna; the curator of the Museum, 

 University of Gottingen; Professor Fr. Zschokke, University of Basel; 

 Dr. C. W. Stiles, Hygienic Laboratory, Washington, D. C; Dr. B. H. 

 Ransom, Bureau of Animal Industry. Dr. John C. Johnson has also 

 very kindly loaned the writer material for study. For the study of Cyclo- 

 coelum halli and Cyclocoelum wilsoni, use has been made of the field notes 

 of W. C. Hall filed with the records of that series. 



Especially to Professor Henry B. Ward under whose supervision the 

 work has been done, the writer desires to express most sincere thanks for 

 the use of his extensive collections and of his library, as well as for his 

 efforts to secure rare material and for the continued deep interest and 

 hearty cooperation which have given the inspiration to finish this work. 



