Igg S. GOTO. 



taculwn vitelli described hy Voeltzkow'^ in Aspidogaster conchicola is 

 homologous with the genito-intestinal canal, and this seems to me to 

 be more probable now that I have shown the homology of the genito- 

 intestinal canal with the Laurer's. For, according to Voeltzkow the 

 receptacidum vitelli arises in Aspidogaster as a solid string, of cells, 

 which reaches the ectoderm on the dorsal side and there spreads out in 

 the form of a funnel. It is therefore exceedingly probable that the canal 

 originally opened to the exterior on the dorsal surface of the body, just 

 as the Laurer's canal now does in the distomes. Hence I regard it as 

 homologous with the Laurer's and therefore wdth the genito-inte&tinal 

 canal. 



It still remains to inquire whether the Cestodes have any organ 

 homologous with the Laurer's canal or with the vagina of the Mono- 

 genea. My answer is that they all possess a homologue of the latter, 

 and some (Ain2)liilina) also one of the former. 



Let us begin our comparison with the unsegmented forms of the 

 tapeworm, which have recently been erected by Monticelli^\ under 

 the name of Cestodaria, into a separate class of the same grade as that 

 of the Trematodes or the Cestodes. Thanks to the investigations 

 of that zoologist the anatomical relations of the genital organs of 

 these forms have been clearly exposed. In Ainpliilina there are two 

 vagina?, one posterior and opening outwards near the posterior 

 end of the body near the external opening of the vas deferens, the 

 other anterior and ending blindly after proceeding for a certain dis- 

 tance forwards from the beginning of the oviduct. Now, everybody 

 will allow that the posterior vagina of this worm corresponds mor- 



1). Voeltzkow — Aspidogaster conchicola. Wiirzburger Arbeiten. Bd. 8, 1888. p. 263 

 & 279. 



2). Monticelli— Appunti sui Cestodaria. Estratto dal vol. V, eer. 2, No. 6, degli Atti deUa 

 E. Accademia deUe Scienze fis. e mat. di Napoli, 1892. 



