THE MYXOSPORIDIA, OR PSOROSPEKMS OF FISHES. 255 



78. Myxobolus linearis Gurley, 1893. PL 36, lig. 2. 



(Psorospemiof rimelodus schw iuul oi PWy stoma fasciatum, Miiller, 1841, Miiller'a 

 Archiv., p. 489, pi. 16, fi}>-. 10 ; ih., Miiller, 1843, Raj-er's Arch, do Metl. comp., 

 pp. 228-229, pi. 9, lig. 10; ih., Robin, 1853, Hist. Nat. d. \6g6X. Parasites, p. 

 300, pi. 14, fig. 11.) 



Myxobolus linearis, Bull. U. S. Fish Com. for 1891, xi, p. 417; ib. of Pimelodes 

 [error] etc., Braun, 1894, Ceutralbl. f. Bakt. u. Parasitenkde, xv, p. 87. 



Cyst not described; myxosporidium uiiknown. 



Spore.— Body very narrow; ]eiiytli,3 to 4 times breadth; cap.sules 

 parallol-appressed, in contact along tbeir entire length; tail simple, 

 occasionally double. 



Habitat. — Cysts in membrane lining branchial cavity of Bhamdiaschod 

 Cuv. & Yal. ; cysts on branchial lamellaj of Pseudoplatystoma fasciatum 

 L., from South American rivers. 



79. Myxobolus schizurus Gurley, 1893. PI. 36, fig. 1. 



(Psorospernis of Esox htcius, Miiller, 1841, Miiller's Arcbiv., pp. 477-478, pi. 16, 



fig. 1; ib., Mttller, 1843, Eayer'a Archir. de MM. Comp., i, pp. 219-222, 



pi. 9, fig. 1; ib., Dujardiu, 1845, Hist. Nat. des Hehuinthes, pp. 643,644; 



ib., Robin, 1853, Hist. Nat. des V<^g6t. Parasites, p. 292, pi. U, figs. 2, 3; 



ib., Lieberkubn, 1854, Miiller's Arcbiv., p. 5; ? ib., Th.^loliau, 1890, Compt. 



Rend, bebdom $oc. Biol. Paris, ii, p. 604; ib., Weltner, 1892, Sitzgsber. 



Ges. Naturf. Freunde Berlin, pp. 29-35.) 

 Myxobolus schizurus, Bull. U. S. Fisb Com. for 1891, xi, p. 417; Myxobolus schio- 



zurus [error] Brauu, 1894, Ceutralbl. f. Bakt. u. Parasitenkde, xv, p. 87. 



Cyst.^ — Whitish, 0-44 to 1-09 mm. (f-^'") in diameter, membrane deli- 

 cate, contents white, unaflected by water, consisting of finely granular 

 matter and spores, the latter motionless. 



Myxosporidium unknown. 



Spore.— Bodj oval, double contoured, resembling and about the same 

 size as the oval blood corpuscle of the fish; leugtU 12 /< (0-0054'"), 

 breadth 6 // (7 /< Eobin; 0-002G'"), thickness about one-half the breadth; 

 border flattened-rotund, marked by a ridge which extends forwards on 

 either side of the shell, projecting slightly in front; tail stout at origin, 

 attenuating gradually, 3 to 4 times length of the body, not articulated, 

 very frequently (probably as a rule) bifurcate at the tip, or for more 

 or less of its length. Untailed forms very rare; capsules 2, of equal 

 size, always diverging posteriorly; remainder of shell cavity filled with 

 a transparent, rarely granular substance, differentiated by refraction 

 from the shell substance. 



JTabitat. — Encysted in the orbit (never found elsewhere) in the cellular 

 tissue of the eye-muscles, in the sclerotic, and between the last and the 

 choroid of young LuciuH IucIuh L. (pike) in May and June. Found in 

 only about 10 i)er cent of the fish examined. Miiller failed to find this 

 disease in the North Auierican pikes examined. 



' These cysts are not to be confounded with similar white entozoan cysts. The 

 latter are of more frequent occurrence in the orbit than the myxosporidian cysts. 

 They are smaller in size (about 0-50 to 0-65 mm.) and have thick walls. Under the 

 microscope the entozoan can be seen moving with transverse wrinklings of its cyst. 



