THE MYXOSPOKIDIA., OR PSOROSPERMS OF FISHES. 



221 



49. Myxobolus ellipsoides, TIi^loLau, 1892. PI. 13, ligs. 3, 4 1 ; pis. 18, 20; pi. 19, iigs. 

 2-^ ; pi. 21, figs. 1, dd, 5, ( ? 2, da-c, c ; r? 4 ; ? pi. 22, tigs. 1-3). 



Synonymy. — The number of known forms habitant on Tinea tinea is 

 large and their rehitions inter se are dubious. By the sei)aration of M. 

 piriformis^ Th61ohan has made a decided advance in the direction of 

 clearness. By its lanceolate shape, single caiisule, and large capsular 

 index it is distinguished clearly from M. ellipsoides and from M. brachy- 

 cystis. It is probable that some of Pfeiffer's degenerated forms should 

 receive a somewhat similar interpretation. His figures are, however, 

 such that in the absence of more definite statements they can hardly be 

 placed. One of them (j)l. 21, fig. 3^) would seem to belong to this 

 si)ecies. The others are entirely indeterminate. 



Cyst. — Thelohan (1890^ p. 203) saw cysts enlarge, become submucous, 

 distending the mucous membrane, which subsequently ruptured, per- 

 mitting the cyst to shell out and fall into the water, where it burst 

 exactly as with the subcutaneous cysts of Gasterosteus aeuleatus. Oysts 

 are found in the comparatively exposed parts, e. g., the subcutaneous 

 and intermuscular connective tissue and in the subepithelial tissue of 

 the branchiie, being absent in the internal organs (air-bladder, etc.). 



Myxosporidium.^ — (a,) In the air bladder: Two forms occur in the 

 air-bladder of the tencli; the first very similar to that found in the 



' See p. 211, footnote 1, and the explanations of the plates. 

 2Th61ohan, Aunal. de Microgr., 1890, ii, pp. 201-2. 



