240 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



60. Myxobolus spheralis Giirley, 1893. 



(Psorospernis oiCoregonna fcra, Clapal•^de, 1874, in Lunol's Hist. Nat. d. poissons 



du bassia du L^inan, pp. 113-14. ) 

 Mijxohulus spheralh, Hull. U. S. Fisli Com. for 1891, xi, p. 415; Myxoholns sphce- 



ralis [cMTor] Hraun, 1891, Ceutralbl. f. liakt. u. Parasitcukde, xv, p. 87. 



Cyst. — Diameter, 0*25 to 0*33 mm. 



Myxosi)()ri(lium unknown. 



Spore. — Very diffeicnt from those contained in the cysts of tjie 

 muscles of the same lish, untailed, perfectly spherical, 9 /u in diameter, 

 containing a single splierical, very strongly refringent "nucleus" and 

 some small granules. Some cysts contain spores with less refi'ingent 

 nuclei ami Avith very numerous small granules. This difference is per- 

 haps only one of age. 



Uahltat. — Cysts imbedded by thousands in the mucosa of the branchiaB 

 of Corcfjonus /era Jur. Their abundance gives to the branchia? a gray- 

 ish color apparent at the tirst glance. 



Remarlis. — 01apar(>de remarks that it might naturally be supposed 

 that a generic bond exists between the small cysts of the branchiae and 

 the large cysts of the muscles, but observation was unable to justify 

 this hypothesis. 



61. Myxobolus sp. incert. PI. 28, fig. 6. 



Psorospernis oi Lnclopcrca sandra, Miiller, 1841, Miiller's Archiv., pp. 480-6, pi. 

 16, figs. 3a-l ; ib., Miiller, 1843, Raver's Archiv. de Mdd. comp., i, pp. 222-6, 

 pi. 9, fig. 3a-I ; ib., Dujardin, 1845, Hist. Nat. d. Helminthes, p. 644; ib., 

 Robin, 1853, Hist. Nat. d. V6g6t. Parasites, p. 295, pi. 15, fig. 5. 



Cysts. — Flat white vesicles or pustules, 1-09 to 2-18 mm. (A to 1'") in 

 diameter, usually few and discrete; contents a small quantily of gran- 

 ular matter, mostly, however, consisting ot the spores. 



Myxosporidium unknown. 



Sjyore. — Almost exactly round, untailed or very rarely (once in 200 

 to 300 times) tailed, the tailed forms occurring in the same cyst and 

 resembling especially M. schizuriis, from which species, however, they 

 differ in having the tiHl no longer or only a little longer than the body; 

 with double-contoured border, thickness equal to one-half the breadth; 

 ridge present; capsules 2, of equal size, converging and appearing as 

 though united by a knot at their anterior extremities (tig. Ga). Among 

 multitudes of typical specimens, Miiller says an occasional one is seen 

 containing 3 bodies, the third being iilaced behind and between the 

 other two. Spore frequently showing a dark punctule just behind the 

 posterior end of each capsule which sometimes sinmlates an oblique 

 line extending from the border to the capsules; at others, a slight 

 projection of the shell. 



Bevelojjment. — Traced (naturally enough, but erroneously ') by Miiller, 

 as follows: (1) Spores occur in which the capsules are no longer at the 



' It must be remembered that Miiller was not aware of the existence of the myxo- 

 sporidium. Recently Miugaijziui lias attempted to revive this view of" the office of 

 the capsules Csec p. 87). 



