STUDIES OX THE ECTOPARASITIC TREMATODES OF JAPAX. 155 



dea Laurer'scben Canals in den Dottergang hd Distommn Jiepaticum." 



Leuckarf regards the genito-intestinal canal as homologous 

 ■with the Laurer's canal and applies this name to the former. He says, 

 " Die Scheide von Pohjstomum integerrimum erscheint hiemach als ein 

 GehUde, welches, da es nehen dem Laurer'schen Kanale existirt, dem- 

 selben nicht hoinolog sein kann." He is of the opinion that the 

 supposed (by Lorenz) opening of the genito-intestinal canal into the 

 vitellarium can no more be regarded as an objection against his view 

 than that the unpaired condition of the vagina in certain monogenetic 

 Trematodes can be advanced as an objection against its homology 

 with* the pau'ed vagina oi Pohjstomum. " Jedenfalls," he warns us in 

 conclusion, " ist das, was man bei den Treniatoden als Scheide 

 bezeichnet, nicht ohne Weiteres iiberall als dasselbe GebUde in Au- 

 spruch zu nehmen und als Laurer'scher Kanal zu bezeichnen." 

 Leuckart is inclined to regard the Laurer's canal as being homo- 

 logous with the vagina of the Cestodes. 



■ Wright and Macallum'^ after describing the canal in Spliy- 

 ranura, say, " How such an economical method of disposing of sur- 

 plus yolk can have been arrived at, whether by the modification of a 

 Laurer's canal or otherwise, we are unable to say." 



Monticelli'' : " Lasciando induscussa la questione, se serve o no 



il canale di Laurer come organo di accompiamento, giudicando 



ora la cose dal punto di vista puramente morfologico, io credo, come 

 del resto parmi pienamente giustificabile, che il canale di Laurer dei 

 digenetici per la sua posizione e il suo decorso, per i suoi rapporti con 

 I'ovidotto intemo e con gli organi femminUe in generale e per la 

 presenza di uno slargamento vesicolare, paragonabUe al ricettacolo 



1). Leuckart— Paraeiten, IL Aufl., 1. Bd., 1886, p. 58-59. 



2). Wright aad Macallum— Sphyranuia Osleri. Joum. of Morphology, VoL I, 1837, p. 42. 



3). Monticelli— Saggio, 1888, pp. 53-59. 



