636 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv. 



HISTORICAL. 



In compiling the bibliogmplw here presented it was quickly found 

 that but a single species, the European Aiyidus foliaceus^ had been 

 studied at all conipleteh'. In fact, with the exception of three papers, 

 one by Dana and Herrick (1837), another b}^ Thorell (1S64), and the 

 third by Kellicott (1877), all the work done outside of mere system- 

 atic enumeration and description of species has been upon this one 

 form. From it has been obtained practically all the knowledge 

 hitherto possessed of the ontogeny of the entire group, with its 

 important l)earing upon their systematic position. Dana and Herrick 

 (1837) do picture a larval Argulus catostomi., but the accompanying 

 description is so brief as to have very little practical value. And 

 Kellicotfs interesting description of a larval ArgnluK (1880) had the 

 misfortune to be published in a periodical that died at the end of the 

 first volume, so that it has remained virtuall}' unknown. 



Moreover, both A. foUaceuK and ^4. catostornl and Kellicott's A. 

 stizostethii are fresh-water forms, and hence absolutelv nothing has 

 been known of the development of the large salt-water representation 

 of the group, which, as we shall see, is \qy\ similar to that of Kelli- 

 cott's species. 



While it does not change the accepted ontogeny in an}' of its great 

 fundamental principles, it will be found to be radically' diflerent in 

 many of the details. 



Although the entire group was thus for a long time represented by 

 the single species, j^'t such a meager representation was more than 

 offset by a remarkably wide distribution. 



A. foliaceus was found quite commonly throughout the larger part 

 of Europe, and ([uickly became well known. Singularly enough, sub- 

 sequent discoveries have brought to light only two other pAiropean 

 species. All the rest of the group, with some exceptions, have been 

 found in American waters, and since the four new species here recorded 

 are also American, it seems as if Kroyer's original statement that the 

 great American continent is the proper habitat of the Argulida? were 

 likely to prove true. 



But since more than half the entire group and eight out of the 

 thirteen North American species are marine, ThorelFs notion that this 

 family is partial to fresh water must be set aside. 



These facts ought at least to correct such statements as that made in 

 Parker and Haswell's Text-book,^ that Argulus "is an external para- 

 site on fresh-water fishes — carp, stickleback, etc.'' 



In the face of such facts it is all the more remarka))le that no Ameri- 

 can zoologist has ever investigated the group. 



Dana and Herrick (1837), Kellicott (1877 and 1880), Gould (1841), 

 and Dana (1852) have each described new species. The first three 



'First volume, p. 531. 



