242 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



63. Myxoboliis transovalis Gnrloy, 1893. PI. 29, iis- 1. 



Bull. U. S. Fish Vom. for 1891, XI, p. 415; ib., Braun, 1891, Cciitralbl. f. nal<t. 

 u. Parasitenkde, xv, p. 87. 



Ci/at. — Existence not evident, the spore-mass appearinj;- to be held 

 tog-other by a small soft gelatinous or mucoid mass which has no atta<,*h- 

 ment to the subjacent connective tissue, as it invariably conies 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 i)riu('i])al guide to 

 its detection. In addition its color when coagulated is a slightij' deeper 

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

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



Myxosporidium unknown. 



Spore. — Length, 6 /,/; breadth, 8 //; 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 sometimes 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 sporoplasra 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 /.i in diameter) nuclei, which are always 

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

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

 ently absent. 



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

 ofFhoxinus {Clinostomu.s)J'ii)ifluloi(les Girard, taken in 4-mile Kun (trib- 

 utary of Potomac Eiver), near Carlins, Va., June 29, 1892 ; collector, the 

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

 1892, no diseased s])ecimens were found. 



64. Myxobolus ? meiiucii Perngia, 1891. PI. 29, fips. 2-7. 



Myxosporidium merhicil Yemghi, 1891, Boll. ,Scieiitif., Pavia, XTII, pp. 22,24, 



figs. 9-11 ; jifi/roholns ^nerhiccii [error], Tli61olian, 1892. Bull. Soc. pliiloniat. 



Paris, IV, pp. 1(56, 178; M. merhicii, (Jurloy, 1893, Bull. U. S. Fish Com. for 



1891, XI, p. 415; ib., Brauu, 1894, Centralbl. f. Bakt. u. Parasitenkdo, 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 spcu form 2 contiguons vacuoles which do uot present the slightest 

 trace of capsules, but ouly a few grauulatious. 



