THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 249 



Cyst not described; myxosporidium unknown. 



Spore. — Perfectly transparent, colorless, much larger than any of 

 Miiller's species, body elongate, strongly ventricose-elliptio, ll-Spt long- 

 by 5'8/f broad; shell bivalve, of firm texture, enabling the spore to 

 retain its shape on drying, splitting open after several days' immersion 

 in water, the resulting median fissure extending nearly to the root of 

 the tail ; tail present, simple, diminishing in thickness from origin to 

 its fine pointed extremity, about as long as or a little longer than the 

 body (in 1 specimen 2^ times that length), often more or less deflected 

 fi'oni the line of the antero iwsterior axis of the body; contents of body 

 cavity perfectly clear, granule-free, showing no trace of structure other 

 than the capsules; capsules 2 (on transverse view only 1) of equal 

 size, ijale yellow, subcylindrical, situated at the anterior pole, diverg- 

 ing posteriorly or adnate to each other along their inner borders ; in a 

 single specimen beginning as a single cylindrical tube (^ the length 

 of the capsules), which divided posteriorly into the 2 capsules; the 

 latter diverging from their origin to their blind posterior extremities 

 (fig. d). Capsules become strongly wrinkled on drying. 



RaMtat. — On Acerina cernua L. ; collected March 14, 1837. 



73. Myxobolus strongyhirus Gnrley, 1893. PI. 31, fig. 5. 



(Psorosperms of Sijnodontis sclial, Miiller, 1841, Miiller's Archiv., pp. 480-1, pi. 16, 

 fig. 2 ; ib., Muller, 1843, Rayer's Archiv. de Med. Comp., i, pp. 222, 227, pi. 9, 

 fig. 2; ih., Robin, 1853, Hist. Nat. de V^g^t. Parasites, p. 295, pi. 14, fig. 4.) 



Myxobolus strongyhirus, Bull. U. S. Fish Com. for 1891, xi, p. 417; Myxobolus 

 strongylura [eiTor], Braun, 1891, Centralbl. Balct. u. Parasitenkde, xv, p.87. 



Cijst.—OYdY 2-18 mm. (1'") in length. 



Mj^xosporidium unknown. 



Spore. — Body blunter anteriorly than in M. scMzurus; length without 

 tail 9/^ (0-0040'") ; breadth, 5-4/y; tail always undivided, very peculiar 

 in being constantly oblique in the longitudinal jjlane, appearing straight 

 when seen in transverse view; capsules, 2, of equal size. Spore some- 

 times showing at posterior end of capsule a dark punctule which occa- 

 sionally causes a slight projection of the shell at this part. 



Habitat. — Encysted in skin of cephalic region of Synodontis schal 

 from the Kile. 



74. Myxobolus monurus Gurley, 1893. PI. 32, figs. 3, 4. 



(PsoTosYierms of Aphredoderus sayanus Ryder, 1880, Amer. Nat., xiv, pp. 211-2, 

 figs. 1, 2; parasite of Aphredoderussavanus^ [error] Th(51ohan, 1892, Bull. 

 Soc. philomat. Paris, iv, p. 177.) 



Myxobolus monurus, Bull. U. S. Fish Com. for 1891, xi, p. 416; ib. of Aphrodode- 

 rus [error] sayanus Braun, 1894, Centralbl. Balit. u. Parasitenlide, xv, p. 87. 



Cyst. — Lenticular, large, bulging^ white, opaque, numerous (about 20 

 in the only fish seen), imbedded in the subcutaneous muscles, arranged 

 as a rule in pairs on the opposite side of the body of the fish; mem- 

 brane very thin; contents, a thick, white, creamy mass, containing 

 multitudes of spores and of excessively minute round granules. 



' " The parasite described by J. Ryder in Aphredoderus savanus constitutes prob- 

 ably a fourth species " [of Th^lohan's genus Henneguya\. 



