CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF 

 THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 

 COLLEGE— 269 



ON THE LIFE-HISTORY OF CERATOMYXA ACADIENSIS, 



A NEW SPECIES OF MYXOSPORIDIA FROM THE 



EASTERN COAST OF CANADA. 



By James W. Mayor. 



Received, December 8, 1915. Presented by E. L Mark. 



CONTENTS. 



Page. 



I. Introduction 551 



II. Diagnosis of Ceratomyxa acadiensis, n. sp 553 



III. Material and Methods 554 



IV. Stages in the life-history of C. acadiensis found in the gaU bladder . 556 



1. Trophic stages 556 



2. Sporogony ■ 559 



A. Formation of the sporoblasts 559 



B. Development of the sporoblast into the spore . . . .561 



C. Structure of the fully formed spore 566 



3. Abnormalities in the structure and development of spores . . . 568 

 V. Summary 569 



VI. Bibliography 570 



VII. Explanation of plates 573 



I. Introduction. 



Uncertainty still exists concerning the main phases of the life- 

 history of the Myxosporidia. Since the two papers by Gurley ('93, 

 '94), the only paper published on the Myxosporidia of American fishes 

 is a short one by Tyzzer (:00). The present paper is a result of the 

 study of the Myxosporidia of the gall bladders of the fishes of the 

 eastern coast of America. A general report of the work has already 

 been published by the author (Mavor, : 15). 



Work was begun on a species of Ceratomyxa from the gall bladder 

 of Zoarces angularis, which showed abundant spores and stages in 

 spore formation. Later a species having spores of the same form and 

 size was found in the gall bladder of Urophycis chuss. A study of 

 the myxosporidian stage of the two parasites showed them to be 

 similar. It was therefore decided to regard them as being the same. 



