THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 



115 



2. rosifion and gronpinf/ of the capsules. — Compared to these all- 

 important characters, the mere numher of the capsules is of minor impor- 

 tance. For, not only does the same genus frequently show 1 or 2, 2 or 

 4, but the number may even vary in the same species, as (apart from 

 the entirely anomalous case of Myxoholus ellipsokles, where " accessory" 

 capsules may develop) Myxidmm HeherMlhnii shows sometimes 2 and 

 sometimes i capsules.^ But what is never varied in the same genus 

 is the topoffrapkio relation of the capsules. Thus in 3[yxoholus, while 

 in number they may be either 2 or 1, they are never arranged otherwise 

 than in one group, or placed otherwise than at the anterior end, and 

 similarly in all the other genera. In Myxidium the capsules are 2 

 or 4, but whether 2 or 4, they are always in two groups at the right 

 and left extremities of the spore. Also in Cystodiscus they are 2 or 4, 

 but always in two groups, which, however, are probably anterior and 

 posterior in position (see p. 278). 



In the following table I have plotted out the i)rincipal characters and 

 indicated their relations to generic lines. 



Comparison of generic characters in the rha'nocijsics. 

 [X=pr6seut; = absent; ( )— less uoual; — = coudition not known.] 



* From analogy and general similarity of appearance, this genu.s ran hardly be other thaubivalve. 

 to. (<S'.) ohhnacheri. 



* Imperfect. Shell and capsules symmetrical; sporoplasm unilateral. 



From this table we may conclude that — " 



1. Henneguya agrees with Myxoholus in every respect but one, the 

 j)resence of a tail. (See also p. 20(5.) 



2. Tlu'lohaii's groups, "il/y.r/r/iVc.s'" and " Chloromyxees,^'' must undergo 

 rearrangeiiKuit (see table below); for clearly (Jlilorotnyxutii, MyxosoDia, 

 and ^i>haros2)ora form a comi)act .group, with which Myxidium has no 

 cliaracter of c()ns('(|uence in common excei)t the absence of a vacuole. 



13albi;uii, ISH'S, Jouni. do Mici 



jr., VII, p. 274, tig. Gig. 



