THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 197 
Spore formation.—Number of spores found in each sporigenous area 
variable, always, however, more than 8, in which respect the present 
species differs from the spores of Palemon and Crangon.! Spores some- 
times free, sometimes 8 together ina common envelope, as in Palemon.? 
Spore.—Size approaching and appearance the same as that of 7. octo- 
spora; ovoid, length 2 to 3 yu, with a clear vacuole in the larger end. 
Habitat—Striated muscles of Astacus fluviatilis (crayfish) from the 
Department of Doubs, France; collected by M. Contejean in 1890, 
Pathological anatomy.—On section the muscles show nearly the same 
appearance asin Paliemon and Crangon ; the fibrille being separated by 
parasitic masses, which in transverse sections appear as numerous 
deeply stained punctules, and which in longitudinal sections assume the 
appearance of irregular chains separating the fibrille; the latter have 
preserved their normal appearance, the strie being perfectly distinct. 
Nature.—The material was available only in alcohol, to which it had 
been transferred from Fol’s liquid. Owing to this, Henneguy and Thé- 
lohan were unable to demonstrate the capsule with filament. The 
similarity to the other species leads them, however, to believe it a 
myxosporidian. 
Hffects.—A notable diminution of muscular vigor was clearly estab- 
lished with the myograph by M. Contejean. 
Epidemics.—In the Department of Doubs this disease has raged with 
intensity among the crayfishes during several years and has caused the 
death of a very great number of individuals. It seems now to have 
disappeared. Moreover, this parasite can hardly be special to the 
watercourses of Doubs, and, remembering the considerable mortality 
caused by it in that Department, it is to be presumed that this hitherto 
unknown organism has played a role in the genesis of the epidemic 
which raged for several years in the East, and which has almost com- 
pletely destroyed the craytishes of that region. 
31. Thelohania octospora Henneguy, 1892. PI. 10, fig. 6; pl. 11, figs. 1-5. 
(Parasite of Palamon rectirostris and of P. serratus, Henneguy, 1888, Mém. 
publiées Soc. philomat. Paris ’Occas. Centen. Fondation, pp. 163-71; ib., 
Thélohan, 1891, Journ. de Microgr., xv, p. 146; ib. of P.. rectirostris, 
Thélohan, 1891, Compt. Rend. hebdom. Soe. Biol. Paris, m, p. 28, name 
only; ib., Thélohan, 1891, Journ. de. Microgr., xv, pp. 146-7; ib., Pfeiffer, 
1891, Die Protozoen als Krankheitserreger, 2 ed., pp. 114-5; ib., Thélohan 
and Henneguy, 1892, Compt. Rend. hebdom. Soc. Biol. Paris, Iv, p. 586.) 
Thelohania octospora in Thélohan, Bull. Soc. philomat. Paris, 1v, pp. 165-6, 
174, footnote; ib., Henneguy and Thélohan, 1892, Annal. de Microgr., Iv, 
pp. 621-27, 629-632, pl. 4, figs. 1-8; ib. Gurley, 1898, Bull. U. S. Fish Com. 
for 1891, x1, p. 410; ib., Braun, 1893, Centralbl. f. Bakt. u. Parasitenkde, 
XIv, pp. 739-40; ib., Braun, 1894, Centralbl. f. Bakt. u. Parasitenkde, 
XV, p. 86. 
1Henneguy and Thélohan, Compt. Rend. hebdom. Soc. Biol. Paris, 1892, 1v, p. 749. 
?Henneguy and Thélohan, 1892, Annal. de Microgr., 1, p. 638. 
