-V - 



Zoologischer Anzeiger 



herausgegeben 



von Prof. J. Victor CarUS in Leipzig. 

 Zugleich 



Organ der Deutschen Zoologischen Gesellschaft. 



Verlag von Wilhelm Engelmann in Leipzig. 



XXIL Band. 24. April 1899. No. 585. 



Inhalt: I. Wissenschaftl. MIttheilangen. 1. Wheeler, The Life -History of Dicyema. 

 2. Bayer, Über einige Elemente der Körperbedeckung bei den ßösselegeln. 3. Fuhrmann, Das 

 Genas Prosthecocotyle. 4. Werner, Ein neues Chamaeleon ans Madagascar (Chamaeleon axillaris). 

 II. nittheil. ans Unseen , Institaten etc. Deutsche Zoologische Gesellschaft. Personal- 

 Notizen. Yacat. Litteratnr p. 153 — 176. 



I. Wissenschaftliche Mittheilungen. 



1. The Life-History of Dicyema ^ 



By William Morton Wheeler. 



eingeg. 17. März 1899. 



Our knowledge of the singular parasites known as Dicyemidae is 

 very largely embodied in two admirable monographs of the European 

 species, one by Prof Ed. van Beneden (1876), the other by Prof. C. 

 O. Whitman (1883). With the exception of a very brief note on the 

 forms which I found in Octopus pmictatus of the Californian coast 

 (1897), no observations have as yet been published on the American 

 species. Although my studies are still incomplete, I have decided, 

 nevertheless, to present some of my conclusions, since on at least one 

 point relating to the reproduction of Dicyema they lead to a new con- 

 ception of the animal's life history. 



The very simple structure of Dicyema may be briefly considered 

 before passing to the question of its mode of reproduction. The body 

 of the animal is long and worm-like and consists of two portions, one 

 of which is a single long, narrow cell, tapering at its ends, the axial, 

 or entoderm cell, the other a single layer of cells completely investing 

 the axial cell and known as the ectoderm. These names, given in the 



1 A preliminary paper read at the annual meeting of the American Morpho- 

 logical Society, Dec. 30th, 1898. 



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