THE MYXOSPORIDIA, 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 suppression of a few of the names proposed. 
Regarding this 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 beredundant. 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 synonymie 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 appended to this paper 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- 
sporidian but now rejected or queried (species Nos. 1 to 26, inclusive), 
excepting only some figures of Psorospermia sciene-umbre, the figures 
of the species referred to on pp. 135-137, and the figures of Lithocystis 
schneidert in Schneider’s Tablettes Zoologiques, 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 only 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 important 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 keep 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 name 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 below has 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 from without inward. 
