THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 273 



92. Chloromyxum (Sphaerospora) dujardini Th^loliau, 1892. PI. 40, fiys. 4-7. 



Synonymi/. — The first 6 references in tlie table, except those to Dujar- 

 din and to Biitschli, represent the same form, the later being mere copies 

 of Miiller. The fusion of the form observed by Dujardin with that ob- 

 served by Miiller is on the authority of Thelohan, who states (letter to 

 the author, 1893) tliat he has observed his Myxosoma dujardini upon both 

 Levciscus rutilus and L. erythrophthalmus, and that he believes that 

 Miiller's and Dujardin's figures represent the same species. Biitschli's 

 form is also probably referable here; size of the last, 0-40 mm. 



Concerning the form observed by him in Leuciscus rutilus, Miiller says : 

 Once there was fonnd on the pseudobranchias (Kehenkicmen) a mass of small yellow 

 cysts. The size of this mass was 4 lines. This time all the cysts contained elongate 

 capsules [spores] with pointed anterior and bluntly rounded posterior ends (tig. 4&). 

 On the flat border the convex surfaces were exactly equal and the 2 diverging vesi- 

 cles were attached interiorly at their points. 



Thus this form was never found coexisting in the same cyst with 

 Myxobolus cycloides. Considering the great frequency of occurrence of 

 the latter species such coexistence would be expected if tliey were 

 merely different forms of one species. Their persistent nonassociatiou 

 thus strongly reinforces the argument in favor of their specific distinct- 

 ness drawn from their different characters. 



Cyst not described. 



Myxosporidium. — Spores imbedded in and held together by an almost 

 diaphanous, ramified, glutinous mass, 1*2.5 to J -50 mm. long, decom]»os- 

 able by water, analogous to the amo'bu', apparently destitute of an 

 envelope (Dujardin). 



Spore. — Oval,i)ointcd anteriorly, broadly rounded i)osterioily, length, 

 10tol2//X0'0()r)l/" to 0-()(>r>4'"); breadth, 7 j.i (0-0034'") untailed; cap- 

 sules 2, of equal size (Miiller). 



Uahitat. — Encysted in the pseudobianchiii' of Lcucisois rutilus from 

 German rivers; branchial lamella' of Leuciscus [Seardinius) erythroph- 

 thalmus from the Vilaine, at Kennes, France, 

 r c 18 



