244 KEPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



(yellow perch) in German rivers and in the Irtisch (Miiller). Scales 

 (Lieberkiihu; Bessels). Disease not coimiion. 



Remttrls, — Bessels"s form seems probably referable here, as he si)eaks 

 of having- observed the, longitudinal splitting into 2 symmetrical halves 

 of an eni])Soid form. 



67. Myxobolus sp. iucert. PI. 29, fijr. 8. 



I'sorospei-iiis of Lenciscus rutihis, v. tl. Bonio, 1886, Haiulb. d. Fisclr/ucbt u. 

 Fiseherei, p. 211, lig. 215. 



Ko d(4Scription. 



Ilabitat. — On Lcuciacus rutilus L. 



68. Myxobolus ?? zschokkei Gudey, 1893. PI. 31, fi.i?. 1. 



(Psorosiicrnis oJ' Con';jo)niK fcra, Zschoklce, 1884, Archiv. de Biol., V, pp. 234-.5, 

 pi. 10, lig. 16; ib., Liutoa, 1891, Bull. U. S. Fish Com. for 1889, ix, p. 101.) 

 Mijxoiolus ?? zschokkei, Bull. U. S. Fish Com. for 1891, xi, p. 416. 



Cyst. — Oval, white, size varying from that of a small pea to that of 

 a large nut; multiple, sometimes as many as 30 on one fish, the largest 

 usually situated in dorsal muscles; cyst membrane thick, very resist- 

 ant, without apparent structure; contents a milky fluid, occasionally a 

 caseous mass, coagulable by alcohol. 



Myxosporidium unknown. 



Spore. — I quote in substance Zschokke's description : 



Body lenticular or oval, a little wider in front than behind; often bearing in front 

 a blunt prolongation; posteriorly one distinguishes 2 " tails" (queues), 6 to 8 times 

 longer than the T)ody, attenuating posteriorly, curved and undulating ; the number 

 of 2 "tails" is constant; at the pole opposite to the "tails" are 2 oval, trans- 

 parent anteriorly-converging vesicles; one sometimes sees, however, an extremely 

 line canal extending from the posterior end of each vesicle to the base of the corre- 

 sponding "tail"; the vesicles then probably play here also the role of receptacles for 

 the " tails." Round refractile globules are also seen at the bases of the vesicles; the 

 remainder of the body is filU'd by a homogeneous plasmic mass, which frequently 

 contracts to tlie center of the body cavity, forming a clearly distinct round or oval 

 mass. 



Habitat. — Encysted in the subcutaneous and superficial intermuscular 

 tissue of Goregonus /era. Observed during April and ]May. Disease 

 stated by fishermen to be of very frequent occurrence. 



Effects. — The skin is irregularly swollen and the scales fall easily. 

 As to myxosijoridiosis of Goregonus, see also p. 233. 



This form is a very puzzling one. As a]>pears from the above 

 description and from the figure (pi. 31, fig. 1), the 2 structures, called 

 by Zschokke "tails" {queues), are seen at one end, and at the opposite 

 end are 2 structures (the " vesicles" of the above description) approxim- 

 ating to the position of and presenting somewhat tlie appearance usual 

 to the capsules, and Zschokke considers them to be the capsules. 

 They converge, as do the capsules of most species, toward the end of 

 the spore, at or near which they are situated, and they diverge in the 

 opposite direction. From these facts one would be inclined to pro- 

 nounce this end (viz, the one at whicli these " vesicles " are placed and 

 toward which they converge) the anterior, and the ox)posite one (the 



