PREFACE. 



In 1900, while a graduate student at the tJniversity of Nebraska, I 

 undertook, upon the suggestion of Prof. Henry B. Ward, of the de- 

 partment of zoology, an investigation relative to the cestodes of birds. 

 So far as the North American fauna yva.s concerned, this topic repre- 

 sented a field which had scarcely been touched. Although a consid- 

 erable number of species had been reported from birds occurring in 

 North America, the descriptions of most of these forms were based 

 upon specimens collected in other parts of the world from birds 

 belonging to species whose range included this continent, or which 

 had been introduced here either wild or in a state of domestication. 



Owing to interruptions this investigation has never been carried 

 out to the extent originally planned. However, a number of hitherto 

 unknown species, and some already named but imperfectly known 

 species, have been studied and described, and a synopsis prepared of 

 the superfamily Tsenioidea to which they belong, together with a list 

 of all the species which have been reported as parasites of birds 

 occurring in North America. This material was presented to the 

 graduate faculty of the University of Nebraska as a thesis for the 

 degree of doctor of philosophy and accepted January 4, 1908. Delay 

 in its final preparation for publication has enabled me to take into 

 consideration a number of recent papers, the most important of which 

 are those of Dr. O. Fuhrmann, the well-known authority on avian 

 cestodes. It has thus been possible to incorporate some valuable data 

 that would otherwise have been omitted. 



To Prof. H. B. Ward, of the University of Nebraska, I am in- 

 debted for much helpful advice during the progress of my investiga- 

 tions, and to Mr. H. C. Oberholser, of the Biological Survey, U. S. 

 Department of Agriculture, for his kindly assistance in selecting for 

 me the names of hosts as recognized by ornithologists at the present 

 time. 



B. H. Ransom. 

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