364 HENRY LESLIE OSBORN. 



2. It passes a period of quiescence encysted in the muscle 

 tissue of various predacious food fishes and in the lymph-spaces 

 of frogs, in various localities ranging from Missouri through Ohio 

 to Pennsylvania, and north as far as Minnesota, Michigan and 

 Ontario, Canada. 



3. It finally reaches an avian host which is some fish-eating 

 bird, such as the bittern or the heron. 



4. The cyst in the fish is a connective tissue structure pro- 

 duced from the endomysium of the host with a special vascular 

 equipment. 



5. The living worms on being artificially liberated from the 

 cysts perform characteristic movements adapted to finding 

 locations in the final host. 



BIOLOGICAL LABORATORY, 

 HAMLINE UNIVERSITY, 

 SAINT PAUL, MINN., 

 March 17, 1911. 



LITERATURE. 

 Braun, M. 



'93 Bronn's Klassen u. Ordnungen. Bd. IV., pp. 306-924. Trematoden. 

 Braun, M. 



'oo Die Arten der Gattung Clinostomum Leidy. Zool. Jhrb. Syst., XIV. 

 Leidy, Jos. 



'85 A Synopsis of the Entozoa, etc., no. 31. Proc. Ac. Nat. Sci. Phila., pp. 

 42-58. 



'87 Notes on some Parasitic Worms, Proc. Ac. Nat. Sci. Phila., p. 24. 

 Linton, Edwin. 



'98 Notes on the Trematode Parasites of Fishes. Proc. U. S. Nat. Mus., XX., 



PP- 597-548. 

 Looss, A. 



'85 Beit, zur Trematoden, Distomum palliatum n. s. u. D. reticulatum n. s. 



Zeitf. w. Zool., XLI. 

 '99 Weit. Beitr. z. Kenntn. der Trematoden Fauna Aegyptens. Zool. Jahrb. 



Syst., XII., pp. 521-748. 

 MacCallum, W. G. 



'99 On the species Clinostomum heterostomum. Am. Jour. Morphol., XV. , 



pp. 697-710. 

 Osborn, H. L. 



'01 Structure of Clinostomum. Science, XIII., p. 378. 

 Stafford, J. 



'94 Trematoda from Canadian Fishes. Zool. Anzeig., XXVII., pp. 681-694. 

 Wright, R. R. 



'79 Contrib. to Americ. Helminthology, No. i. Proc. Canad. Inst., I. 



