154 



s. GOTO. 



modified tissue around the terminal part of the vas deferens, which has 

 been set off from the surrounding mesenchyma by a membrane or a 

 layer of muscular fibres, I have thought it advisable to abandon its use 

 altogether and to adopt the terminology used in this paper. The term 

 " cirrus " has been used by many writers for the spines either of the 

 penis or of the genital atrium. 



3. The prostate gland (= Körnerdriise of Lang and Graff, 

 Penisdriise of Ijima) has been described in other members of the 

 Plathelminthes, and I believe] I have succeeded in demonstrating it 

 in the monogenetic Trematodes generally. 



4. Homology of tlie canalis genito-intesti nails — I shall now proceed 

 to discuss the homology of this problematic canal and endeavour to 

 throw some light on the question ; and in doing this I shall be led to 

 consider also the homology of the vagina and the uterus of the 

 Cestodes as well as the vagina of the ectoparasitic Trematodes and the 

 Laurer's canal of the Digenea. Before, however, expounding my own 

 opinion, it will not be out of place here to bring together the views of 

 preceding writers. 



The ""enito-intestinal canal of the Monoo:enea was discovered in 

 its right connection by Ijima^^ (^Polgstomum, Axine, Octohothiuni). 

 To the question, which of the two canals, the vagina or the genito- 

 intestinal canal, is the homologue of the Laurer's canal -^ his answer 

 is not decisive either way. He says, " Was nun den Zusammen- 

 hang der Scheide mit dem Oviduct anbelangt, so findet er entweder 

 direkt (Calicotyle, Pseudocotyle, Axine) oder indirekt durch den Dot- 

 tergang statt. In ersterer Hinsicht finde ich keine wesentliche Ab- 

 Aveichun": von den meisten von uns bekannt o-e wordenen Fallen des 

 Laurer'schen Kanals. In zweiter Hinsicht erinnere ich an das Oeffnen 



1). Ijima — Ueber den Zusammenhang d. Eileiters mit d. Verdauungskanal bei gewissen 

 Polystomeen. Zool. Anz., Jahrg. VII, 1884, p. 635. 



2). The use of this name I shall confine to the Digenea. 



