THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 275 



viz : (1) That bisporogeiiesis must be admitted as a (very striking) generic 

 feature; aud (2) that if, as Perugfa asserts, Mijxoholus meiiucii possesses 

 this character, it is in all probability a Ceratomi/xa, and not a MyxoboJufi. 

 And two facts confirm this latter view, viz: The improbability in Myxo- 

 holus of a gall-bladder habitiit and the rarity of spores whose breadth 

 exceeds the length. Perugia's species is, however, provisionally left 

 under Myxohohis, on account of his positive statement as to the i^resence 

 of an iodinophile vacuole. 

 The following is an abstract of Thelohan's paper: 



Besides the species formerly published ' in which the uiyxosporidium 

 L '^o® -I produces but 2 spores, I have since confirmed the same ]ieculiarity in a 

 rather large number of new forms in the gall-bladders of certain Mediterranean fishes. 

 All these 2-sporing species belong to ny family " Myxidi^es," the greater part of them 

 being clearly referable to Ceratomyxa, while the others, by successive modifications 

 of spore-form, establish a transition between that genus and Spharospora. This 

 last connects the 2-sporing species with the many-sporing, and at the same time, by 

 its habitat, the free species to the tissue-imbedded forms. 



There is thus no absolute separation between the 2-sporing and the other Myxospo- 

 ridia. The 2-sporing always live a free amoeboid life in the bile-fluid and exhibit a 

 very gi-eat motility, owing to specialized pseudopodia heretofore described. 



These 2-sporing Myxospondla with localized pseudopodia and rapid movements 

 represent the most elevated type of organization. As regards the interpretation of 

 the facts, are they perfected types derived from inferior, or are they 

 [} age 430] ^-^^ primitive type, the others, especially the tissue-imbedded species, 

 being forms degraded by a more pronounced (a, so to speak, more intimate) parasit- 

 ism f Th^lohan favors the latter view. Great stress is to be laid upon the pro- 

 gressive increase in the number of spores occurring pari pasiiu with degradation 

 of form and increase of parasitism, such increase of reproductive elements being 

 always one of the most constant attributes of parasitism. 



84. Ceratomyxa arcuata Th^lohan, 1892. 



Compt. Rend. Acad. Sci. Paris, cxv, p. 1091. 



Cyst none. 



^Iijxosporidnim. — Of variable form, diameter apparently not exceed- 

 ing 35 or 40 //; destitute of prolongations. Endoplasm finely granular 

 aud homogeneous, containing some scattered fatty globules; destitute 

 of spherules. Pseudopodia ectoplasmic, lobed; the filiform variety 

 absent. 



Sjwre. — Kelatively very small; length, 5 //; breadth, 40 //. 



Habitat. — Gall-bladder of Onns tricirratus { = ]\JofeIla tricirrata) col- 

 lected at Roscofi", in August, 1892. 



Remarlis. — This differs from the other species of the genus priiu-i- 

 pally in its much smaller size. 



85. Ceratomyxa agilis Thclohan, 1892. 



Compt. Rend. Acad. Sci. Paris, cxv, pp. 9fi2-3. 



Mi/xospofidium. — Attaining a maximum length of 85 //, and a maxi- 

 mum l)ri'a(lth of 20 //; assuming varicms forms, most frequently elong- 

 ated, subcylindric, a little swollen at the nuddle. One end (which on 

 account of being constantly foremost in progression is to be regarded 



» Compt. Rend. Acad. Sci. Paris, 1894, cxviii, pp. 428-430. 



