THE MYXOSPOEIDIA, OR PSOROSPERMS OF FISHES. 67 



one, too many specific names have been introduced. In answer might 

 be pleaded the difficulty, in a first attempt of this kind, of judging exactly 

 how many species to recognize, and it is not impossible that future 

 experience may require the suppressionof afewof the names proposed. 

 Eegardingthis contingency, however, as one of the incidents of an initial 

 revision, the author will view with considerable equanimity the relega- 

 tion to synonymy of such names as may prove to be reduiidant. Finally, 

 as regards this branch of the subject, it should be stated that the main 

 indication seemed to be the building up from the literature of a series 

 of synonymic units which could be later, if necessary, welded into a 

 more compact specific synonymy. This indication has been fulfilled, 

 nearly all the units here constructed consisting merely of an original 

 description and copies of the same by subsequent authors. 



The plates api^ended to this i^aper include every published figure of 

 every myxosporidian species (species Nos. 27 to 102, inclusive); further, 

 every published figure of every species formerly regarded as myxo- 

 si)oridiau but now rejected or queried (species Xos. 1 to 26, inclusive), 

 excepting only some figures of Fsorospermia scicence-umbrcc, the figures 

 of the species referred to on pp. 135-137, and the figures of LitlwcysUs 

 schneideri in Schneider's TabJettes Zoologiqucs, which work was not 

 accessible. 



In the course of my studies I have been perplexed by the usual num- 

 ber of quotations without any or with onlj^ cryptographic references. 

 In the hope of obviating this in the future, intelligible references are 

 given for all statements made and, it is believed, for all imjiortant facts. 



A number of new terms are introduced in this paper, as it is con- 

 sidered very desirable to have the definiteness and specialization of 

 terms keej) pace with the increasing detail of knowledge. They are 

 defined on pp. 120-122. An exceedingly instructive instance of the con- 

 fusion resulting from the application of the same narne to two entirely 

 different structures is afforded by the history of the filaments (see 

 pp. 87-88). If such non-discrimination were to continue far, we should 

 have to construct an elaborate synonymy for every structure as well 

 as for every species. 



The lack of a uniform (often, indeed, of any) system of arrangement 

 of data forms, unfortunately, a marked feature in many papers. With 

 very few exceptions the scheme given belowhas been adhered to through- 

 out this paper. It may not prove to be the best possible, but if it serve 

 to secure the adoption of some regular order (what particular one mat- 

 ters, perhaps, not a great deal) it will have fulfilled its object. The 

 principles underlying it are: 



{a) Describe all structures, etc., in the order of their occurrence in the 

 life cycle, beginning with the adult; the process of formation of a struc- 

 ture to precede the description of that structure. 



(b) Describe structures in order of position fi'om without inward. 



