THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 241 
anterior end, but in the middle, and have their axes parallel (fig. 3h). 
(2) Numerous mother vesicles [pansporoblasts] are seen containing 2 
spores standing on edge, in contact, with their longitudinal planes 
parallel; such spores show capsules in their interior in the usual place. 
(3) Rare cases occur (fig. 6e) where the mother vesicles contain 3 such 
spores; these correspond to the rare cases in which the contents of the 
spore consist of 3 parts. He concludes that the capsules are the germs 
of new spores. 
Habitat.—Encysted in skin of the external or internal surface of the 
opercles, in the rays of the branchial membrane, on upper surface of 
head or on the fins of Stizostedion lucioperca (= Lucioperca sandra), pike 
perch, from German rivers and from the Don. Disease very frequent, 
mostly in May and June. Miiller found it in from 20 to 25 per cent of 
the young fishes examined. They were taken during the first of the 
winter. 
62. Myxobolus globosus Gurley, 1893. Pl. 28, figs. 1-3. 
Bull. U. S. Fish. Com. for 1891, x1, p. 415; ib., Braun, 1894, Centralbl. f. Bakt. 
u. Parasitenkde, Xv, p. 87. 
Cysts.—V arying from very minute toa maximum of 0-5 mm., elongate- 
elliptic or rod-shaped, apparently (judging from ease of rupture) with 
a very thin membrane; color, whitish; contents, spores. 
Myxosporidium unknown. 
Spore.—Globose, subcircular in outline, untailed; length, 7 or 8 y; 
breadth, 6 or 7; thickness, 5u. Shell substance thin, very trans- 
parent, composed of 2 valves (superior and inferior in position), which 
present a heavy ridge whose width nearly equals one-third of the thick- 
ness ofthe spore. Valves equally and very convex on their external 
surfaces, appearing symmetrical on either side of the ridge. Capsules, 2, 
of equal size, rather strongly diverging; capsular index somewhat more 
than 0-50. Nuclei 3 or 4, viz: the 2 pericornual and 1 or 2 others, the 
latter the usual and presumably the fully developed condition (see p. 
92). Vacuole present. Owing to the great convexity of the sporoplasm 
surface and the great thickness of its substance, it is not so clearly 
outlined as usual. 
Habitat—Encysted on the branchial lamelle of Hrimyzon sucetta 
oblongus Lac. (= Catostomus tuberculatus Le Sueur'), chub sucker. 
This species was found upon fishes from the first 3 localities; on those 
from the fourth none were detected. 
The following is the record of fishes examined: 
U.S. Nat. 
Mus. No. Locality. Date. Collector. 
20523 King tonne Olsens scese see beeesesoncbas: J. W. Milner. 
25573 | Columbia,S. C -..---.-.--.- | Mar. 21, 1880 | Marshall McDonald. 
20105 | Tributaries Fox River, | 
Mississippi... =< 2-.---- 15 - beseaceesseSo6 S. F. Baird. 
20254 | Near Piermont (? Pier- { 
TOTS INE Mose apeicoeasoe oat sane racs S. F. Baird. 
1 Fide Jordan & Drayton, Bull. 12, U. S. Nat. Mus., pp. 100, 145; var. oblongus, fide 
Prof. B. W. Evermann. 
FC 16 
