Nachdruck verboten. 

 Uebersetzungsrecht vorbehalten. 



Anatomical structure of Aspidogaster conchicola. 



By 



Dr. Joseph Stafford B. A., Toronto. 



(From the Zoological Institute of the University of Leipzig.) 



With Plates 36—39, 



Introduction. 



Aspidogaster conchicola has been the subject of frequent observ- 

 ation and many zoologists have added to its literature. Few, however, 

 have devoted to it a lengthy investigation, or even subjected any of 

 its organs to the methods of modern research. 



It is not my intention so summarize here the results of previous 

 writers ^) and needlessly extend this work. Those results, important 

 as they were to me, have been found in numerous cases inadequate 

 but much of them, so far as correct, has been necessarily included in 

 new and, it is hoped, more definite and thorough descriptions. 



The aberrant form and the direct development or arrested meta- 

 morphosis of this worm, as well as the passing of its whole parasitic 

 existence and attainment of sexual maturity in the one invertebrate 

 host merit our most accurate attainable knowledge ; which is all the 

 more desirable also since its systematic position among the Trema- 

 todes has been an unsettled question. Until lately it was held to 

 belong to the M o n o g e n e a , and its direct development seems to 

 favor this view ; while in structure, habits and the form of the embryo 

 it presents many affinities to the Digenetic Trematodes, in 

 which group it is placed by Leuckart ^\ who, from a comprehensive 

 generalization of the relations between parasites and their hosts, 



1) A list of the works on Aspidogaster is given at the end of this 

 paper. 



2) Parasites of man, 1886. 



32* 



