STUDIES ON THE ECTOPARASITIC TREMATODES OF JAPAN. ^9 



fig. S ; ?]. XXIY, iig's. G, 9, & 10 ; PI. XXY, figs. 1, 3, 5, 8, & 9). 

 It then proceeds either staight forwards or else a little to the left, 

 makina" all the while niiineroiis small hut close convolutions : and 

 then tin'nino' more or less towards the rio-ht on the dorsal side of the 

 penis, enters the latter close to its hase. Here it forms a swelHng, 

 the ve.'iiciihi seniinalis^ and then again contracting to a very small caii;d 

 arid traversing the penis parallel to its central ca^■itv, opens finally 

 int(^ this at some distance from its apex, in some species on the t(^]) of 

 a papilla (PI. XXIT, fig. 4).^* 



St.-Pemy-* distinguishes in Trisloiuiim three ])ortions of the 

 vas deferens, vi.:., (1) the single "canal seminal," ('2) the '• vésicule 

 ('jacidatrice " situated in the penis and receiving at one of its ends the 

 narrow termination of the seminal can;d and contiimed at the other 

 into the (3) '' canal ('jaculateur," with which it communicates hv a 

 very short, narrow canal. It does not, however, seem to me necessary 

 to distinguish these parts. As I have mentioned abt^ve, there are 

 numerous constrictions in the course of the vas deferens; but these 

 are cpiite irregular, and can not, in my opinion, he taken as marking 

 off distinct portions of the vas deferens from each other. It 

 is, however, convenient to designate that jiortion of the vas deferens 

 wliich lies within the penis the ductus cjacuJatorlus, although it should 

 be remembered th;it in many species this is not the only portion that 

 is concerned in ejecting the s]ierm fluid. In TrUtomum. and Epihdella, 

 this portion is provided with circular muscular fibres (PI. XXII, fig. 

 I ; PI. XXVI, fig. 7). 



In Epihdella a short vas efferens proceeds from each testis ; but 

 s<wn unites with its fellow and forms a single vas deferens. This 



1). For minuter details see the description of species. 



2). G. St.-Remy— Contribution à l'étude de l'appareil (génital chez les Tristouiiens. Archives 

 de Biologie, T. XIT, 1892. p. 5 et iufra. 



