224 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



conjugation. And still further, in some individnals the filaments 

 instead of lying along the borders of the valves, extend themselves in the 

 direction of the axis of the body, and, reuniting themselves for a variable 

 distance, constitute the simple or double caudal prolongation that 

 Miiller and other observers describe as a siDeeific ^character of certain 

 psorosperms. (See also p. 207.) 



Concerning these, Biitschli^ states that he coiild find no evidence 

 whatever of the existence of such ribbons, either in the whole spore or 

 in the separated valves. He seems to think that such ribbons are an 

 illusion due to an abnormal extrusion of the capsular filaments. 



Th61ohan's observations s^em to throw some light upou this discrep- 

 ancy. This observer 2 says that he has never seen them except in the 

 present species. They are frequently absent, yet the spores split open 

 perfectly. Having found all possible transitions between the ribboned 

 spores and spores evidently monstrous and abnormal, he regards the 

 ribbons as structures, accidental rather than fundamental and neces- 

 sary to the development of the spore. 



HaUtat. — Thelohan gives this as the branchisie, air bladder, liver, 

 intestine, and spleen (last^f7e letter to author, 1893) of Tinea tinea L. 

 (tench). Balbiani says the Myxosporidia are always confined to the 

 short anterior portion of the air bladder. 



Speaking collectively of a poorly delineated and very probably multi- 

 specific group of forms, Pfeiffer says that perfectly developed forms 

 occur on the branchiie and in the air bladder, this stage of development 

 being possibly connected with an abundance of oxygen. In the gall 

 bladder incompletely developed forms occur, with 3, 1, or no capsules; 

 also entirely undeveloped forms, destitute of a bivalve shell, compara- 

 ble to the Microsporidia or to the pseudo-navicellje found in Lumbricus. 

 Transition forms to the Coccidia also occur. Possibly (from Pfeiffer's 

 figure) M. ellipsoides may also occur in the air bladder or gall bladder. 



Effects. — The Myxosporidia do not confine themselves to existing 

 cavities. Thus, in the kidney of Tinea tinea, Thelohan (1890, p. 200) 

 has seen the tissue of the organ invaded while the tubes remained free 

 (see also the above description of changes produced in the structure 

 of the air bladder by the myxosporidium found in that organ). 



50. Myxobokis ? sp. incert. PI. 22, fig. 4. 



Psorosperms of Cyprinus leuciacus, Miiller, 1841, Miiller's Archiv., p. 486; ii., 



Dujardin, 1845, Hist. Nat. des Heliniiitlies, p. 644; ib., Leuckart, 1852, 



Archiv. f. physiol. Heilkde, xi, p. 436, fig. 21c, d; ib., Eobiu, 1853, Hist. 



Nat. des V^g6t. Parasites, p. 299. 



Synonymy. — This is little more than a collection of references to 



spores found on ^'Cyprinus leueiscus.''^ Eobin's mention is, however, 



certainly the same as Miiller's. 



Cyst and myxosporidium unknown. 



iZtscbr. f. v/iss. Zool., 1881, xxxv, p. 633; Bronn's Tbier-Reicli, 1882, i, p. 598. 

 ^Compt Keud. Acad. St;i. Paris, 1880, cix, pp. 920-1. 



