Preliminary notes on GaMrodes para siti cum 

 Korotneff, with remarks on its 

 systematic position. 



By 



Taku Kotnai, 



Zool. Inst., Sci. Coll., Tokyo Imp. Univ. 

 With 2 textfigurcs. 



The peculiar parasitic cœlenterate, Gastrodes parasiticum KOROT- 

 NEFF, living in the test of Salpa, has been so imperfectly known that 

 very diverse opinions were entertained as regards its systematic position. 

 KOROTNEFF 1 , the discoverer of the animal, referred it at first to the 

 Narcomedusae and later to the Actiniae, while HEIDER 3 regarded it to 

 be a degenerate ctenophoran. 



In the spring of 1919, it happened in Misaki that swarms of Salpa 

 fusiformis appeared for several successive weeks and offered opportunities 

 to collect specimens of the parasitic cœlenterate in question. Examina- 

 tion of the parasite clearly showed at once that we have to do with a 

 ctenophore, and in fact with a ctenophore probably belonging to the 

 remarkable group of Platyctenea. 



The animal is found imbedded in the Salpa test, invariably with 

 its ventral surface turned towards the main body of the host The 



1) KOROTNEFF, A. (1888). Cunoctantha und Gastrodes. Z. \v. Z. Bel. 47. 



2) „ „ (1891). Zoologische Paradoxen. Z. W. Z. Bd. 51. 



3) Heidf.r, K. (1S93). Ueher Gastrodes, eine parasitische Ctenophore. Sitzb. Ges. 

 Nat. -Freund in Berlin. (This paper has remained inaccessible to me ; its contents are known to 

 me only from the citation in Dei.AGE and Herouard's " Traité de Zoologie Concrète," T. 2, 

 2 me. Partie, Coelentérés, p. 75g, and from the abstract in the " Zoologischer Jahresbericht " 

 f. 1893, Coelenterata, p. 9. 



