THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 71 



GENERAL DESCRIPTION OF THE SUBCLASS MYXOSPORIDIA. 



I.— NOMENCLATURE AND DEFINITION. 



Sup.KixGDOM PROTOZOA. 



Class Spokozoa Leuckart, 1879 (emendated). 



The following is Leuckait's clefiiiitiou ^ verbatim, with the exception 

 of the proposition of the Grc[j<(rini(la as the type order, a proposition 

 that is imphed by Leuckart's laiigaage. The w^ords inclosed in brackets 

 should, as shown by subsequent observations, be omitted from the 

 class definition. 



Unicellular parasites [of stable body-form], destitute [of pseudopodia and] of 

 ciliie, covered with a smooth, more or less solid cuticle. At the anterior end not 

 seldom a proboscidiform attachment-apparatus. Movements on the whole little 

 striking?, worm-like or feebly amoeboid. Mode of life always parasitic; nutrition 

 by endosmosis. Reproduction by more or less hard-shelled spores (pseudonavicelhe ; 

 psorosperras) formed in the interior of the protoplasm in variable but very consid- 

 erable numbers,- either progressively or simultaneously (in the latter case at the 

 termination of growth and alter encystment). Germinal portion of spore consisting 

 of falciform protoi)lasmic rods {Grenarlnlda; Coccidia) or a siugle protoplasmic mass 

 (Myxosjwridia) ; type order Gregariiiida. 



Subclass Myxospohidia. Biitschli, 1881, 



Zoolog. Jahres-Ber. f. d. J. 1880, I, p. 162; ih., Biitschli, 1881, Ztschr. f. wiss. Zool., 

 XXXV, pp. 630, 650; ib., Biitschli, 1882, Broun's Thier-Reich, i, p.590; ih. of all 

 subsequent authors; Mi/xosjwridw (Psorospermida) J. Miiller)^ Ziirn, 1882, 

 Die thierischeu Parasit<ni, Weimar, p. 816; Myxospora'' (error) M(5gnin, 1885, 

 Compt. Rend, hebdoni. Soc. Biol. Paris, ii, p. 447; subclass Myxosporidia, Lan- 

 kester, 1885, Encycl. Brifan., 9 ed., xix, p. 855; " Psorospermidte J. Miiller,"^ 

 Koch, 1887, Encyklop. d. gesammt. Thierheilkde u. Thierzucht, iv, p. 94. 



TIIK SUBCLASSIC DESIGNATION, 



Miiller, in 1S41, denominated the forms observed by him merely as 

 "Psorospermien." Everything points to the conclusion that this name 

 was used merely indefinitely as a group designation. He neither 

 proposed it as a generic name nor did he anywhere latinize it. He 



iDic Parasiten des Mensehen, 1879, 2 ed., jj. 241. 



2 Compare Bisporogenesis in index. 



3 An error; Miiller did not propose any such family, Ziirn's deiinition is quoted 

 to show the errors (italics) : 



"Older 4. Myxosporidm {rsorospevmidw, J. Aliiller). Frequent in and on fishes 

 and Amphibia. The nuclens-lcss, often granulated protojjlasm, is surrounded tube- 

 like by a cuticle. From the young protoplasm of these tubes, single or double con- 

 toured, fusiform, oval, or round spores originate tvithout previous encysiment. In the 

 spore originate one or several germs, mostly resembling a nucleus-less, but somewhat 

 granulated plasma-globule, or representing a needle-shaped (stabformige) body. The 

 spore membrane often provided with 1 or 2 filaments) bursts in order to free the only 

 very rarely motile germs." 



■• " P8orosj)ermies des poissons ou Myxospora de Biitschli." 



