THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 239 



56. Myxobolus sp. incert. PI. 28, fig. 4. 

 C^'st and inyxospondiuin unknown. 



Spore. — Broadly elliptic; length, 14 /<; breadth, 10 fx-, thickness, 5 yu; 

 shell bivalve; valves equally convex; ridge iudex about 0-25. Caj)- 

 sules 2, equal; capsular index not quite 0-50. Sporoplasm showhig a 

 clear, round space, without doubt the A^acuole. 



Habitat. — Body cavity of Garasslus carassius L. (goldfish), from Ger- 

 many. 



Bemarlcs. — For this species I am indebted to Dr. C. W. Stiles, who 

 mounted the spores in Leipsic. The exact locality whence the host 

 came is unknown. The specimen was mounted unstained in Farrant's 

 solution. For this reason the vacuole conld not be stained or the 

 nuclei be determined. 



57. Myxobolns ? obesus Gurley, 1893. PI. 28, fig. 7. 



(Psoiosperm of the '-Ablette," Balbiani, 1883, Journ. de Microgr., Aai, p. 203, 

 fig. 43; ib. Buibiaiii, 1884, Lec^ous sur les Sporozoaiies, p. 133, fig. 39.) 



Myxobolus obeaus, Bull. TI. S. Fish Com. for 1891, xi, p. 415; ib. of Alburntis 

 lucidtts^ Brauu, 1894, Centralbl. f. Bakt. u. Parasiteukde, xv, p. 87. 



No descrii)tiou. 



Habitat. — Un Alburnus albunius L. 



58. Myxobolus cycloides Gurley, 1893. PI. 28, fig. 5. 



(Psorosperius of Cyprinus rutihis, Miiller, 1841, Miiller's Archiv., pp. 481, 

 486, pi. 16, fig. id-fj; ib.,- Creplin, 1842, Wiegnianu's Archiv. f. Xatur- 

 gesuh., 1, p. 63 (footuote); ib., Miiller, 1843, Rayer's Archiv. de. M6d 

 comp., I, p. 226, pi. 9, tig. 4d-</ ; i6., Rayer, 1843, ibid., p. 269; ib., (pars) 

 Robin, 1853, Hist. Nat. V^got. Parasites, p. 299, pi. 14, fig. 6.) 



Myxobolus cycloides, Bull. U. S. Fish Com. for 1891, xi, p. 415; ib., Braun, Cen- 

 tralbl. f. Bakt. 11. Parasiteukde, xv, p. 87. 



Cyst. — Not described. Creplin states that the membrane is very 

 delicate and that it is "dissolv^ed" by water. 



Myxosporidium unknown. 



Spore. — Subcircular-ovate or broadly rounded-elliptic, resembling M. 

 circular is; length, 12 /< (0-0054'"). 



Habitat. — Encysted, most frequently on inner surface of opercle and 

 particularly on the i)seudobranchiai {Nebenkiemen) of Leuciscu.s rutilus 

 from German rivers. Disease of very frequent occurrence, principally 

 in May and June. Creplin's specimens were taken May 8, 1835, and 

 January 31,1839. 



59. Myxobolus sp. incert. 



Myxo«poriiliau spore of Guidon, Th(?lohau, 1889, Coiupt. Rend. Acad. Sci. Paris, 

 CIS., p. 921. 



Spore. — Vacuole present; maximum number of nuclei, 3. 



Habitat. — On the " Gardon.^^ At present this form is entirely indeter- 

 minate, as M. Thclohan inform.s me (letter, 1S<)3) that (Jardon is applied 

 indiscriminately to b(»tli Leiiciscun rutilus and L. erythrophthabnus. 



I Tiie question between the two specific names is merely that of the advisability 

 of the use of a spiMifie name identical witii the geueric. 

 * Creplin compares hie form to Miiller's, fig. 4d, 



