250 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



Myxospoiidiuiu mi known. 



ISpore. — Body lenticnlar or slightly obovate; tail present (rarely 

 absent), thick at origin, attenuating gradually, more or less curved, 

 between 2 and 3 times as long as the body, undivided; capsules, 2, of 

 equal size, subparallel, on longitudinal view seen to be eccentric. 



Habitat. — Encysted in subcutaneous intermuscular tissue of Aphredo- 

 ilerufi sayanns Gilliains (pike perch), taken near Woodbury, 1^. J. • 



75. Myxobolus macrurus Gnrley, 1893. PI. 32, fig. .5; pi. 33, figs. 1-4. 



{Myxosporidia of Hylognathus nuchalis, Evermann, 1892, Bull. U. S. Fish Com. 



" for 1891, XI, p. 76). 

 Mijxooolus macrurus, Bull. U. S. Fish Com. for 1891, xi, p. 416 ; ib. of Hypogna- 

 thus [error] nuchalis, Brauii, 1894, Centralbl. Bakt. u. Parasitcnkde, xv, 

 p. 87. 



Cyfit. — Midtiple (usually 15 to 20 or more), the size of a pin-head, some- 

 times separated, more frequently in contact, forming elongated masses 

 G mm. by 2, or less, imbedded in the subcutaneous connective tissue; 

 almost invariably situated upon some portion of the head. Out of a 

 multitude of cysts upon more than 80 tish, I have seen but one exception, 

 a cyst situated at the base of the pectoral tin, a few millimeters behind 

 the head. The great majority of the cysts are concentrated in 2 lines 

 along the 2 halves of the inferior maxilla between the bone and the skin. 



Myxosporidium unknown. 



Spore. — Tailed; body rounded-oblong, 10 or 11// long, 6 to 8/< broad, 

 4/1 thick. Shell substance tbiu, colorless, perfectly transparent, very 

 resistant to the strongest acids and alkalies, not stained by any of the 

 reagents tried. Valves 2, superior and inferior, unequally convex. 

 Superior valve with a very convex outer surface, to which corresponds 

 internally a surface deeply concaved for the reception of the larger por- 

 tion of the capsules and sporoplasm. Inferior valve outwardly convex- 

 flattish, with a shallow line of depression across the middle portion of 

 its external surface, to which corresponds on the internal surface a 

 broad, gentle ridge, marking the space between the capsules and the 

 sporoplasm. Eidge forming the anterior continuation of the tail, at the 

 anterior extremity of the spore, projecting slightly in transverse view 

 (optical section), as a blunt, nasute process. 



Tail substance somewhat less transparent than that of the shell, 

 completely dissolved by sulphuric acid (cold, concentrated) almost 

 (usually entirely) invisible in balsam, the species then appearing 

 untailed. Tail very long when complete (30 to 40// orless), the veryatten- 

 uate posterior portion easily (and consequently frequently) broken off, 

 the tail then appearing short, thick, and blunt. Tail consisting of 

 a single long, posteriorly-directed median piece, and of two short, 

 anteriorly- directed lateral pieces. Median piece, usually straight, fre- 

 quently, however, more or less deiiected to the right or left, or upward 

 or downward, thick at its origin, attenuating gradually thence to the 



