ON THE DISTRIBUTION AND MODE OF OCCURRENCE 



IN THE UNITED STATES AND CANADA OF 



CLINOSTOMUM MARGINATUM, A 



TREMATODE PARASITIC IN 



FISH, FROGS AND BIRDS. 



HENRY LESLIE OSBORN. 



CONTENTS. 



1. Geographical Distribution of Clinostomum marginatum 350 



2. On the Cysts in the Black Bass 354 



3. Behavior of Worms Liberated from Bass-cysts 357 



4. On the Cysts in the Frog 360 



5. On the Occurrence of the Worm in the Heron 362 



i. GEOGRAPHICAL DISTRIBUTION OF Clinostomum marginatum. 

 The fluke referred to in this paper was first noticed in this 

 country in 1856 by Joseph Leidy, in the intestine of the pike of 

 the Delaware and in cysts attached to the gills of the sun-fish 

 (Enpomotis vulgaris} near the city of Philadelphia. Leidy applied 

 the name Clinostomum gracile to it. This generic name after 

 many years of non-use has come into current usage since the late 

 revision of the Trematodes which has received such impetus 

 from the work of Looss ('oo) who recognizes this name and Braun 

 ( ! oo) who in a revision of the genus in 1900 recognizes eight species 

 of the genus Clinostomum, among them C. marginatum. In 

 1879 R. Ramsey Wright found cysts attached to the gills, branch- 

 iostegal membranes and pectoral fins of the yellow perch (Perca 

 flavescens] at Toronto, Ontario, which he recognized as being iden- 

 tical with the Clinostomum gracile of Leidy and called Distomum 

 gracile. His observation extended the geographical range of 

 the species to the St. Lawrence River system. In the same paper 

 Professor Wright reported the finding of D. gracile in the bittern 

 (Botaurus minor] a fish-eating bird which was the first information 

 as to the definitive host of the worm. Looss in 1885 published 

 an account of the structure of a fluke which had been found en- 

 cysted in the muscle of a silurid fish from Porto Rico. He gave 



350 



