FOREWORD 



Within the last 20 to 25 years an increasing nunaber of works have p. 3 



been devoted to the monogenetic trematodes. Despite this, our knowledge 

 is still far behind that of other parasitic groups, particularly digenetic tre- 

 matodes and tapeworms. For this reason I consider it my duty to publish 

 the results of my almost 30 years of research in the field of phylogeny and 

 systematics of the Monogenoidea considering that, despite the numerous and 

 irritating gaps which are clearly apparent to me, my work nevertheless will 

 be fruitful in the development of further research in this very interesting 

 group in the practical as well as the theoretical sense. 



I am prompted to this publication by the memories of constant and 

 friendly exhortations of my teacher, Valentine A. Dogiel, whose desire it 

 was to see this work completed. V. A. Dogiel was vitally interested in these 

 questions which inspired me, and much of what is written here is the result 

 of mutual discussion and lively disputation which took place during all the 

 years of our common work, beginning with the expedition to the Aral and 

 Caspian Seas in 1930-32, It is impossible to express with words the feeling 

 of gratitude which I experienced when I remember and evaluate the influence 

 of V. A. Dogiel on my life and scientific work. 



The completion of the present research was greatly impeded by 

 the fact that, until recently, I could only work sporadically because of the 

 overload caused by other duties. Consequently, a warmer feeling comes 

 from the remembrance of constant help and friendly attention which was 

 given my by my friends in the Department of Parasitology and the Ichthy- 

 ology Laboratory of the Zoological Institute of the Acadenay of Sciences, 

 U. S. S. R. I also received considerable help from collaborators of the 

 Laboratory of Fish Diseases, VNlORKh (AU-Union Scientific Research 

 Institute of the Fish Industry of Lakes and Rivers riobis ) and the Depart- 

 ment of Invertebrate Zoology of Leningrad University. 



Academician E. N. Pavloski, showed constant attention to my 

 work, and he often helped to organize many of my field trips. ,^ 



i 



During the writing of this work I received great support from two 1 



of my friends, A. A. Strelkow and A. S. Monchadsky without whose help my p. 4 'I 



work would have remained unfinished for a long time. Their friendly criticism 

 and advice constantly helped my work. I must also mention the help of A. 

 A. Strelkow and many of our common field trips to the Pacific Ocean, the 

 Sea of Japan and the Sea of Okhotsk. 



The shaping up of this work, which required great labor, was 

 accomplished with the collaboration of L. F. Nagibina. The majority of 



the original drawings were made by her. In addition to that, for many 

 years L. F. Nagibina constantly helped me in my experiments and field 



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