THE MYXOSPOKIDIA, OR PSOROSPERMS OF FISHES. 195 



Pansporoblast splierical, average diameter 15 to 18//; membrane 

 tliin, transparent, containing, besides fully developed spores, sporo- 

 blasts in different stages of development, some of tliem measuring 2-5 

 to 3 yu, and containing one or several colored granules representing 

 nuclei. 



Spore. — Ovoid, resembling that of Glugca anomala; length, 3 /<; 

 breadth, 1-5 to 2 /<; a single capsule with a filament is present; large 

 extremity showing a mass refractory to staining fluids, the remainder 

 of the spore cavity containing sporoplasm, and a body apparently repre- 

 senting the nuclear element of the spore, staining strongly with reagents, 

 and in certain cases decomposable into separate granules whose num- 

 ber never exceeds 4. 



Eahitat. — Muscles of Cottus scor]}io (sculpin); position interfibrillar. 



Effects. — Diseased mass forming small white streaks of an average 

 size of 5 to 6 mm. by 3 mm., consisting of spores. The fibers alfected 

 increase in bulk; they are filled with the pansporoblasts disposed 

 without regular order between the fibrillge, which latter become sepa- 

 rated and distorted, without, however, presenting any alteration of 

 structure or diminution in the clearness of their tran verse striation. 



in. THELOHANIA Henueguy, 1892. 



Etymology : Thdlohan. 



In Thelohan, Bull. See. philomat. Paris, iv, p. 174, footnoto; ih. Henneguy, in 

 Henneguy and Tli61olian, Aniial. de Microgr., Paris, 1892, iv, p. 639; ib. 

 Gurley, 1893, Bull. U. S. Fisli Com. for 1891, xi, pp. 109-410; ih. Brauu, 

 1893, Ceiitralbl. f. Bakt. u. Parasiteukde, xiv, pp. 739-740; i6. Braun, 1894, 

 Centralbl. f. Bakt. u. Parasiteukde, xv, p. 86. 



Befinition^ (provisional as regards negative characters). — Glufjeidce 

 destitute of a myxosporidium and in which the pansporoblast pro- 

 duces constantly 8 spores; pansporoblast membrane subpersistent as 

 an octosporophorous vesicle ; type T. giardi.'- 



Henneguy and Thelohan remark that in this genus the spores unques- 

 tionably approximate those of Glugea anomala and those oi Pleistopliora. 

 The number of spores formed in the pansporoblast and the absence of 

 a myxosporidium differentiate Tlieloliania from Glugea. On the con- 

 trary, the last character and the subpersistence of the pansporoblast 

 membrane as a sporophorous vesicle, approximate it to Fleistophora. 



' Henneguy's definition is: 



"Spores pyriform, with one polar capsiile at the small extremity and, at the opposite 

 extremity, a clear vacuole with contents not colorable by iodine. Sporol)lasts pro- 

 ducing only 8 spores surrounded by an envelope persisting after the formation of 

 these last; no plasmic mass, properly speaking." 



As constituted by Henneguy the genus included only 3 species, T. octonpora, T. (jhtrdi 

 and T. contejeani. 



•Type proposed 'by the author in Bull. U. S. Fish Com. for 1891 (1893), xj, p. 410. 



