PART I 

 MORPHOLOGY AND BIOLOGY OF MONOGENETIC TREMATODES 



CHAPTER I 

 MORPHOLOGY OF MONOGENETIC TREMATODES 



The present chapter contains a description of the morphology of p. H 

 monogenetic trematodes expressed in such a way as to serve as a basis for 

 further considerations of the evolution of the group. In connection with this, 

 not all parts are described with an equal degree of completeness, and on the 

 other hand, the appraisal of such morphological characteristics is made 

 from the point of view of the phylogenetic researcher and not of the (pure) 

 morphologist. 



We shall also indicate that the material described has, itself, 

 an independent significance, because neither in native nor in foreign litera- 

 ture is there anything comparable at the present time. 



In Russian literature monogenetic trematodes^ which were sepa- 

 rated by us into an independent class (Bychowsky, 1937), are considered 

 with digenetic. trematodes. Consequently, as a result of the greater at- 



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Referring to textbooks and morphological references, because in literature 

 on systematics our system of parasitic flatworms is acquiring a greater 

 number of adherents. 



tention to digenetic trematodes, the information on the morphology of the 

 monogenetic trematodes is given in such a fragmented fashion that it com- 

 pletely fails to impart an accurate impression concerning the group. 



Among foreign works the most solid description of monogenetic 

 trematodes is the essay of M. Braun (Braun, 1889 to 1893) which became 

 extremely antiquated although, in some respects, it preserves its signifi- 

 cance even to the present time. The second among the essays is the work 

 of O. Fuhrmann (Fuhrmann, 1928) very succinctly written by a non-specialist, 

 and it also has become antiquated. During recent years there appeared two 

 more essays concerning the group which interests us, one by Ben Dawes 

 (Dawes, 1947) which is devoted to monogenetic and digenetic trematodes, the 

 other by Nora Sproston (Sproston, 1946) which is devoted especially to mono- 

 genetic trematodes. Both essays have sections on morphology, but they are 

 extremely short and serve mainly as an introduction to the systenaatic parts. 



