THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 211 
Spore.—Ot the form and size of Chloromyxum dujardini. Capsule only 
1, situated on one side of the anterior end, obliquely directed. 
Habitat.—On Labeo niloticus from the Nile. 
35. Myxobolus piriformis Thélohan, 1892. Plate 13, fig. 3 (pars), 4 (pars); pl. 18. 
(Psorosperms of the tench (pars) Balbiani, 1883, Journ. de Microgr., VII, pp. 
197-198, fig. 66 b,c, ? d—f; ib. (pars) Balbiani, 1884, Légons sur les Sporo- 
zoaires, pp. 125-6, fig. 47b, c, ? d-f; pl. 4, figs. 1, 2, 3A (pars)}, ? 3B,C; 
? ib. (pars) Pfeiffer, 1890, Die Protozoen als Kranheitserreger, 1 ed., pp. 
* 48,55, fig. 16; ? ib. (pars) 1891, 2 ed., p. 132, fig. 56. 
Myxobolus piriformis, Bull. Soc. philomat. Paris, Iv, p. 177; ib., Gurley, 1893, 
Bull. U. S. Fish Com. for 1891, x1, p. 414; ib., Braun, 1893, Centralbl. f. 
Bakt. u. Parasitenkde, xiv, p. 739; ib., Braun, 1894, Centralbl. f. Bakt. u. 
Parasitenkde, xv, p. 86. 
Synonymy.—M. Thélohan informs me (letter, 1893) that : 
M. piriformis has very probably been seen by Remak, although his figures and his 
descriptions do not prove it absolutely (pl. 5, fig. 5). He does not figure the polar 
capsules, but his figures almost certainly belong to the species in question. 
Fig. 8 represents 2 spores from the kidney? of the tench, which I do not know to 
what species to approximate. The presence of 2 capsules separates them from MW. 
piriformis. The form of its spores and the small size of the capsules do not permit 
of its approximation to any of the forms that I have encountered. 
The typical spore of MW. piriformis contains but 7 polar capsule. As in all species, 
one can find monstrous spores which inclose 2 capsules, but they have seemed to me 
very rare. This species is often accompanied, above all in the spleen of the tench, 
by MW. ellipsoides. Almost all the spores with 2 capsules, represented by the authors, 
belong, I believe, to the spores, more or less monstrous, of this last species. 
Balbiani considered M. piriformis a degraded form of IM. ellipsoides. I have been 
able to convince myself that this mode of view is not correct. It is a species abso- 
lutely distinct and well characterized, as I have been able to determine by numerous 
observations. 
After reading the above, I restudied the synonymy as between this 
species and J. brachycystis, and can not but feel that all of Remak’s 
figures are referable to 1 species, which probably is, as Thélohan thinks 
and contrary to my former opinion,’ distinct from his M. piriformis. 
The following are the conclusions at which I have arrived: 
(a) Remak’s figures are referable to 1 species. His fig. 8 (referred to 
in the second paragraph of the above quotation) is not from the kidney 
but from the spleen. There appears to me to be, especially in view of 
Remak’s statements which tend to show that he considered the question 
carefully, no ground for a separation between these 2 developed spores 
1 The figures in the rows on Balbiani’s plate Iv, fig.3, are numbered in order from 
left to right, in the reproduction of it on pl. 18, fig. 3. The proper specific refer- 
ences of some of the figures of groups 3 and 4, on that plate, are dubious. The fol- 
lowing is about all that can be safely said at present: 
Indeterminate: Figs. 3 B,C; 4d-f. (either MW. piriformis or M, ellipsoides). 
Myzxobolus piriformis: Figs.3 A, Nos. 1, 2,6; 40, c. 
Myzxobolus ellipsoides: Figs. 3 A, Nos. 3, 4,5, 7 (the last with some certainty, the 
rest probably, ‘“‘abnormal” spores); 4a. 
2These spores (Remak’s fig..8) are from the spleen. 
3 Bull. U. S. Fish Com. for 1891, x1, p. 409, second footnote, where it is stated that 
1 Myxobolus species possesses, perhaps inconstantly, a single capsule. At that time I 
inclined to fuse M. brachycystis with M. piriformis. 
