196 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
30. Thelohania contejeani Henneguy, 1892. Pl. 10, figs. 4, 5. 
‘Parasite of crayfish, Henneguy and Thélohan, 1892, Compt. Rend. hebdom. 
Soc. Biol. Paris, Iv, p. 749.) 
Thelohania contejeani, in Thélohan, Bull. Soc. philomat. Paris, rv, p. 174, foot- 
note; ib., Henneguy and Thélohan, 1892, Annal. de Microgr., Iv,-pp. 
637-9, pl. 4, figs. 26-7; ib., Braun, 1893, Centralbl. f. Bakt. u. Parasitenkde, 
XIV, pp. 739-740; ib., Dubois! (Raphzl) 1893, Recherches de pathologie 
comparée sur la peste des écrevisses, Compt. Rend. hebdom. Soc. Biol. 
Paris, V, pp. 158-9, figs. A,B; ib., Gurley, 1893, Bull. U. S. Fish Com. for 
1891, x1, p. 410; ib., Braun, 1894, Centralbl. f. Bakt. u. Parasitenkde, 
Xv, p. 86; cf. La Maladie des Kerevisses en Allemagne; Bull. Mensuel Soe. 
Nat. @Acclimat. France, February, 1884, p. 200 (transl., Bull. U.S. Fish 
Com. for 1884, Iv, pp. 299-302). 
Cyst—None. Parasitic mass producing an opacity of the affected 
muscles, as in Palemon and Orangon. Opacity more difficult of obser- 
vation than in the last, on account of the greater thickness of the test; 
easily detected, however, on the inferior surface of the abdomen. 
Adult.—In some places only spores are seen; in others small plasma- 
spheres, containing a variable number of nuclei, occur. These are 
evidently developmental stages, but a full series could not be found. 
1This observer noted 2 (entirely distinct) parasites, viz: one which Henneguy 
and Thélohan pronounced a fungus, and one which he determined to be Thelohania 
contejeani. 
1. The former he describes as follows: 
Spore.—Cellules elongate, ovoid, cylindrical, or strangulated toward the middle, 
according to the degree of development. Shell double-contoured; protoplasm 
vacuolate, escaping amceboidly through a small lateral orifice. Spores apparently 
not capable of growth in nutritive fluids. 
Habitat.—Confined to the intestinal canal of the diseased crayfishes. The observa- 
tions were made in June and July (1892), the months of maximum severity of 
the epidemic. 
Crayfish epidemic.—Causes: Alterations of streams by industrial or agricultural 
products can have only a subordinate and local influence. 
Areainvaded divisible into 3 zones: (1) Lake Mantua (and its outlet to the sea, — 
the river Ain); formerly renowned for its crayfishes, which constituted an important 
revenue; now destitute of crayfishes. (2) The Merloz rivulet, an affluent of the 
lake, containing sound and diseased crayfishes, the latter showing the symptoms of 
the pest. (38) The sources or Doye des Neyrolles feeding the lake and the Merloz 
rivulet, from which latter it is separated by a dam, above which all the crayfishes are 
healthy. A 
The stoppage of its advance by the dam and its inability to growin nutritive fluids 
caused Dubois to suspect it to be an animal (possibly a sporozoan) which ascended 
the watercourse from the sea, perhaps brought bya fish. Thélohan and Henneguy, 
however, from an examination of his material, believed the form to be a fungus. 
The Distome described by Baer in 1827 (when no epidemic existed), to which Harz 
attributes the crayfish epidemic, was sought for in vain. : 
2. Thelohania contejeani.—Feeding experiment: Sound crayfishes were isolated 
in reservoirs and fed, some with butcher’s meat, and others with the flesh of trout, 
carp, pike, and roach. After three months those fed on roach showed parasites in 
the abdominal muscles. This parasite was identical with Thelohania contejeani. 
Dubois asks: Do relations exist between the parasite found in the muscles and the 
intestines in October, and that found in July in the abdomen? 
