[3] ENTOZOA OF MARINE FISHES OF NEW ENGLAND. 455 



In the descriptive part of this paper I have confined my attention to 

 the Cestoidea and the Acanthocephala, and with two exceptions, viz, 

 Dibothrium aluterce and Uchinorhynckus sagittifer, to adult forms. 



In the determination of genera I have been guided principally by 

 Diesiug's Revisions. Accepting the characters there enumerated, I 

 have been compelled to create three new generic names, viz : Spongio- 

 bothrium, Crossobothrium, and Phoreiobothrium. 



For the determination of species I have made use of the publications of 

 Eudolphi, Diesing, P. J. Van Bencden, Dujardin, Von Linstow, Wagener, 

 Krabbe, Olsson, Eschricht, Leuckart, Kiichenmeister, Ziirn, Von Sie- 

 bold, Leidy, Cobbold, and others. 



Systematic work on the Entozoa is attended with much difficulty on 

 account of the confusion in which the earlier literature is involved. In 

 this connection I take the liberty of quoting a brief passage from Von 

 Linstow's " Compendium der Helminthologie," Hannover, 1878 : 



" The number of well-founded species is indeed not quite so great as 

 the list indicates, for a host of older names, especially originating with 

 Eudolphi, figure in it, of which typical examples are no longer in ex- 

 istence, and which have been described imperfectly or not at all, so that 

 they must remain forever an unsolved riddle. For example, many rudi- 

 ments of Tarnice discovered by this author, whose enumeration has been 

 of not the least advantage to science, and many descriptions of older 

 date have not since been recognized. One comes from their contem- 

 plation often in great perplexity of mind, and does not really know how 

 they ought to be represented. Moreover, to make the entire literature 

 effective was impossible, since too many species are described in such 

 a way that it is not possible to recognize them again, and other specifi- 

 cations are so improbable that for this reason they must remain uncon- 

 sidered ; * * * when further the description of a new species is dis- 

 posed of with an enumeration of the length and breadth, when, finally, 

 for new species only the place where they are found is given, together 

 with or without an accompanying description, as is to be found in many 

 works, then I think I am not at fault in citing such publications only 

 in limited amount." 



It has been my endeavor to give as full a description of each species 

 considered as the material at baud would justify. When only alcoholic 

 specimens were accessible I have mentioned the fact in the proper 

 place. 



As the development of many of the Cestoidea seems to be quite differ- 

 ent, even in closely related forms, it is very important that the sys- 

 tematic work which is done on them be so done as to leave no doubt in 

 the mind of the investigator what species is being described, whether 

 the name adopted for it holds or not. Appreciating the value of figures 

 in establishing the identity of species, I have therefore not included 

 in this paper descriptions of any forms unless accompanied with suffi- 

 cient figures to make future identification reasonably certain. 



