242 EEPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



63. Myxobolus transovalis Gnrley, 1893. VI. 29, fig. 1. 



Biill.U. S. Fish Com. for 1891, xi, p. 415; ib., Brauii, 1804, Centralbl. f. Bakt. 

 u. Parasiteukue, xv, p. 87. 



Cyst — Existence not evident, the spore-mass appearing to be lield 

 together by a small soft gelatinous or mncoid mass which has no attach- 

 ment to the subjacent connective tissue, as it invariably comes away 

 with the scale. It forms a thin discoidal mass situated in the center 

 of the concave under surface of the scale. When at its thickest it 

 elevates the scale slightly, and this elevation is the principal guide to 

 its detection. In addition its color when coagulated is a slightly deeper 

 yellow than that of the surrounding tissues. It is exceedingly difficult, 

 in fact nearly impossible, to detect its presence in the fresh state. 



Myxosporidium unknown . 



Spore. — Length, 6 ^; breadth, 8 fi; shell thin; substance almost per. 

 fectly transparent, insoluble in concentrated sulphuric acid, bivalve; 

 the valves superior and inferior in position, equally ventricose, with a 

 narrow ridge ; valves separating easily when placed in cold concentrated 

 sulphuric acid, also vsometimes in strong glycerin, or when the mass is 

 rolled under the cover slip. 



Capsules: Two, of equal size, containing a coiled filament extruded 

 under the influence of glycerin and of sulphuric acid; capsular index 

 about 0-50. 



Sporoplasm: The great convexity of the sporoplasm renders it diffi- 

 cult of determination whether the deeper iodine-stained portions rep- 

 resent merely greater thickness or a vacuole. Sometimes the latter 

 view was suggested by the rather sharp outline of such deeper-stained 

 areas. Hydrochloric acid alcohol carmine stains 2 (very rarely 1 only) 

 comparatively large (1 to 1-5 fx in diameter) nuclei, which are always 

 and plainly situated in the sporoplasm with a site by preference along 

 or near one of its concave anterior borders; pericornual nuclei appar- 

 ently absent. 



Habitat. — Under scales on external surface (mostly on posterior half) 

 oiPhoxinus [Clinostomus) funduloides Girard, taken in 4-mile Kun (trib- 

 utary of Potomac River), near Caiiins, Va., June 29, 1892; collector, the 

 author. Among fishes collected from the same locality, August 29, 

 1892, no diseased specimens were found. 



64. Myxobolus ? merlucii Perugia, 1891. PL 29, figs. 2-7. 



Myxosporidium merlucii Perugia, 1891, Boll. Scieiitif., Pavia, xiii, pp. 22,24, 



figs. 9-14; MyxohoJm merhiccii [error], Thdloliau, 1892, Bull. Soc. philomat. 



Paris, IV, pp. 166, 178; M. merlucii, Gurley, 1893, Boll. U. S. Fish Com. for 



1891, XI, p. 415; ib., Braun, 1894, Centralbl. f. ]?akt. u. Parasitenkde, xv, 



p. 87. 



Myxosporidium. — Occurring under various forms; no differentiation 



of ectoderm; no pansporoblast membrane. The spores are expelled at 



their maturity from the myxosporidium. Perugia adds: 



I have also seen form 2 eoutigiioiis vacuoles which do not present the slightest 

 trace of capsules, hut only a few granulations. 



