THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 175 



5. Balbiania rileyi Stiles, 1893. PI. 3, figs. 1-5. 



(Psorosperms of mallard duck, Leidy, 1875, Proc. Acad. Nat. Sci. Phila., xxvii, 



p, 125). 

 Balbiania rileyi, Bull. 3, Bur. An. lud., Dept. Agric, i)p. 80-84, pi. 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 navicellae; length n/n', 

 habitat, encysted in interstices of muscles of the mallard duck (Anas hoschas 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 rejieatedly observed since by 

 Eetzius, 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 uot unnaturally be supposed that in this 

 instance " psorosperm " referred to a myxosporidian. 



Recently Dr. C. W. Stiles has reexamined 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 hoschas. 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 O-KJ 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 (2/y) 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 chjpeata), and the mallard 

 or tame duck [Anas hoschas). Development unknown. 



North America. (?) Philadelphia, Pa. (Coues; Leidy); St. Louis, 

 Mo, (Riley); Clear Lake, Cal. (Brett); Minnesota (Liiger); Quebec 

 (Belanger). 



Type material deposited in the TJ. S. Il^fttional 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. 



