THE MYXOSRORIDIA, OR PSOROSPERMS OF FISHES. 245 
one from which the “tails” proceed) as the posterior. Zschokke, how- 
ever, states that he has often seen a fine canal running from the (on 
the above supposition) posterior end of each capsule to the base of the 
“tail,” and expresses his belief that, in this species as in those observed 
by Balbiani, the function of the “vesicles” is to contain the “ tails.” 
Both he and, subsequently, Linton! perceived the anomaly which, upon 
his view, is presented by this species, but neither of them discusses it at 
length. It is almost as difficult to reverse the position of the spore and 
consider the “ tails” as corresponding to the filaments which in other 
species are extruded from the capsules, as this view would necessitate 
the admissions that the capsules are placed at and converge toward 
the posterior end of the body, and that the filaments are extruded from 
their posterior ends, a state of things occurring in no other known 
species.” I may add that the filiform aspect of the so-called “tails” is 
quite different from that shown by the stout tails of other species, 
while it closely resembles that of the capsular filaments. 
69. Myxobolus cf. creplini. P1.30. 
Myxosporidian spore of Hsox lucius, Weltner, 1892, Sitzungs-Ber. Ges. Naturf. 
Freunde Berlin, 1892, pp. 28-36, figs. 1-16. 
The fish was a spawner, weight estimated at 1 kilo; it showed a mass 
of milk-white eggs whose contents consisted of myxosporidian spores, 
a granular mass, and afew yolk granules. The material was first exam- 
ined by Hilgendorf, who recognized the myxosporidian spores. 
Spore dimorphous, untailed and tailed forms occurring. Anterior 
end more or less bluntly rounded. Posterior end showing great differ- 
ences, aS a rule gradually drawn out without any boundary into the 
thin tail. More rarely the alternation is sudden and the tail is then 
delimited from the body. With some spores there is found at the 
place of transition of the body into the tail a wing-like expansion, 
which lies at the border of the spore. The untailed spores have the 
posterior end rounded, much blunter than the anterior; otherwise they 
are formed entirely like the tailed. The tailed spores are of a fusiform 
shape. 
Relation of untailed to tailed: It might readily be believed that the 
tailed develop from the untailed by the appearance of a short stump, 
which would subsequently grow in length and breadth; thus the body- 
length of the 2 forms is about the same, the whole length of the tailed 
consequently exceeding that of the untailed only by the length of the 
tail. Also the maximum width is about the same for both spore-forms. 
Shell consisting of 2 thick almost always unequally arched? valves 
which can gape apart anteriorly for more than half their length; by 
1Bull. U. S. Fish Com. for 1889 (1891), p. 101. 
2M. diplurus has (if Biitschli’s figure be correct, pl. 36, fig. 4) the capsules poste- 
riorly placed, but their convergence and divergence is not evident, and nothing is 
known about the capsular filaments. 
3Weltner refers to his figs. 8 to 11, in which the inequality of valve-convexity 
might perhaps be the result of the oblique positions of the spores. 
