THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 71 



GENERAL DESCRIPTION OF THE SUBCLASS MYXOSPORIDIA. 



I.— NOMENCLATURE AND DEFINITION. 



SUBKINGDOM PROTOZOA. 



Class Sporozoa Leuckart, 1879 (emendated). 



The following is Leuckart's definition"^ verbatim, with the exception 

 of the proposition of the Gregarinida as the type order, a proposition 

 that is implied by Leuckart's language. The words inclosed in brackets 

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

 class definition. 



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

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

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

 striking, worm-like or feebly amoeboid. ]Mode of life always p.arasitic; nutrition 

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

 psorosperms) 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 after encystment). Germinal portion of spore consisting 

 of falciform protoplasmic rods {Gregarinida ; Coccidia) or a siugle protoplasmic mass 

 {Myxosporidia) ; type order Gregarinida. 



Subclass MYXOSPORIDIA. Biitschli, 1881. 



Zoolog. .lahres-Ber. f. d. J. 1880, i, p. 162; il., Biitschli, 1881, Ztschr. f. wiss. Zool., 

 XXXV, pp. 630, 650; ih., Butschli, 1882, Bronn's Thier-Reich, i,p.,590; il. of all 

 subsequent authors; Myxosjwridw (PsorospermidiB J. Miiller)'* Ziirn, 1882, 

 Die thierischen Parasiteu, Weimar, p. 816; Myxospora* (error) M^gniu, 1885, 

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

 kester, 1885, Encycl. Britan., 9 ed., xix, p. 855; "Psorospermidaj ,J. Miiller,"* 

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



THE SUJ5CLASSIC DESIGNATION. 



Miiller, in 1841, denominated the forms observed by him merely as 

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

 was used merely indefinitely as a grouj) designation. He neither 

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



' Die Parasiten des Menschen, 1879, 2 ed., p. 241. 



^Compare Bisporogenesis in index. 



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

 to show the errors (italics) : 



"Order 4. Myxosporidce (rsorospermidw, J. Miiller). Frequent in and on fishes 

 and Amphibia. The nucleus-less, often granulated protoplasm, 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 encyslment. In the 

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

 granulated plasma-globule, or representing a needle-shaped {stahformige) body. The 

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

 very rarely motile germs." 



■• " Psorospermies des poissons ou Myxospora do Biitschli." 



