STUDIES ON THE ECTOPARASITIC TREMATODES OF JAPAN. 153 



A penis similar to that oîTristomiim occurs according to Poirier,'^ 

 among the Digenea, in Distomiim davatum, D. verrucosiuu, D. msicjm 

 and D. Mcrjnini. In these forms, however, it has a much simpler 

 structure than in Tristomum; and it should moreover be remarked that 

 in the two last-mentioned species it is also traversed by the uterus 

 and that in D. vcrnicosum it does not prominently project into the 

 genital atrium, and somewhat approaches inform that of Onclwcofijlc in 

 having its tissue distinctly separated from the surrounding mesenchyma. 



It will be observed that in my descriptions I have nowhere used 

 a term corresponding to " Cirrusbeutel (poche de cirrhe, tasca del pene)" 

 so often met with in the literature on the Trematodes and the Cestodes. 

 This I have done with an express purpose. The term "Cirrusbeutel" 

 and those that correspond to it have been used to designate various 

 structures by different Avriters. Leuckart"^ uses it for "ein keulen- 

 oder birnformiofes Ornfan von ansehnlicher Grösse und wesentlich 

 muskulöser Beschaffenheit, ... der das .Endstück des Samenleiters, 

 den sog. Ductus excretorius, in sich einschliesst." Poirier^^ on the 

 other hand uses it in D. insigne and 1). Mcgnini, in which a distinct 

 penis is present, for an ovoid sac around the terminal portion of the 

 vas deferens, which has a distinct wall and contains the prostate glands 

 together with a comparatively small quantity of connective tissue; 

 while Monticelli^^ seems to use it for the penis itself, reserving the 

 word penis for that terminal portion of the vas deferens (i. c. the ductus 

 ejaculatorius) which is evaginated during copulation. In view of these 

 various sisrnifications of the term, and considering: that the so-called 



CD ' O 



" Cirrusbeutel" is not a hollow organ, but «imply a mass of specially 



1). Poirier — Z. c. 



2). Leuckart— Pcarasiten. II. Anfl., 1 Bd. p. 43. 



3). Poirier-;, c. pp. 551 & 553 ; PI. XXXIII, fig. 1 & PI. XXXIV, fig. 1. 



4). Mouticelli— Studii, p. 80 et infra. 



