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THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. £5 
5. Balbiania rileyi Stiles, 1893. Pl. 3, figs. 1-5. 
(Psorosperms of mallard duck, Leidy, 1875, Proc. Acad. Nat. Sci. Phila., xxvi, 
p. 125). 
Balbiania rileyi, Bull. 3, Bur. An. Ind., Dept. Agric., pp. 80-84, pl. 2, figs. 1-5. 
Dr. Leidy’s description may be summarized as follows: 
Cyst, oval, white, 2 to 4 mm. long, 0°7 mm. thick. Contents, myriads of fusiform 
corpuscles. Spores fusiform corpuscles resembling minute navicellw; length 17y; 
habitat, encysted in interstices of muscles of the mallard duck (Anas boschas L.). 
Nature.—Leidy says that— 
Similar bodies were first discovered by the late Prof. Miiller and described by him 
under the name of psorosperms. They have been repeatedly observed since by 
Retzius, Robin, and others, in the muscles and other parts of fishes, and they are 
usually regarded as vegetable parasites. Though the mallard is not a fish-eater, the 
bird may have become infected by eating infected fish. 
From this extract it might not unnaturally be supposed that in this 
instance “ psorosperm” referred to a myxosporidian. 
Recently Dr. C. W. Stiles has reéxamined the subject. He studied 
material from two hosts and five localities, including one lot labeled: 
Oval, smooth bodies, no limbs. In muscles of Mallard. Anas boschas. Dr. E. 
Coues. Ex. Jan. 29, 1890. 
The following is the diagnosis: 
Parasite 1 to 6 mm. long by 0-48 mm. broad; rather fusiform, ends not 
sharply pointed. Cuticle not striated, about 2, thick. Central core 
not coloring and not containing falciform bodies. Peripheral zone 
as broad as central core (0-16 mm. to 0-16 mm.) or even broader, coloring 
in various liquids (acid carmine; methyl blue), containing numerous 
falciform bodies. Form of meshes irregular but elongated radially. 
Falciform bodies 12 to 14 long, more pointed at one extremity than 
at the other; containing a very distinct nucleus (21) which stains clearly 
in acid carmine or methyl blue, and which contains several chromato- 
phile granules; vacuole quite indistinct. 
Habitat.—Intermuscular connective tissue of ducks, the shoveler or 
shovelbill duck or spoonbill duck (Spatula clypeata), and the mallard 
or tame duck (Anas boschas). Development unknown. 
North America. (?) Philadelphia, Pa. (Coues; Leidy); St. Louis, 
Mo. (Riley); Clear Lake, Cal. (Brett); Minnesota (Liiger); Quebee 
(Bélanger). 
Type material deposited in the U.S. National Museum, in the Bureau 
of Animal Industry, and in collection of Stiles, Washington, D. C. 
Specimens are also to be found in the Army Medical Museum, Wash- 
ington, D. C., and in collection of Leidy, University of Pennsylvania, 
Philadelphia, Pa. 
In conclusion, although “measly duck” is not very appetizing in 
appearance, there are no grounds for believing that it is dangerous to 
man, 
