84 S. GOTO. 



of the body but also in the anterior part, extending forwards almost 

 as far as the brain ; in the second species also, the numerous testes 

 extend forwards almost up to the anterior suckers on both sides of 

 the ovary ; while in both species of Oetocotyle described in this paper 

 the anterior testes are arranged in a sinrfe row on the left side of 



o O 



the ovary, while the posterior ones are arranged in two irreguLar 

 rows. In some other species also, as in Onchocotyle and most species 

 of Tristomum, the foremost testes more or less overlap or surround 

 the ovary ; but in the majority of species the testes are situated wholly 

 behind the ovary. In most species again, they occupy the median 

 portion of the body between the main trunks of the intestine, but in 

 some species of Tristomum {Tr. ovale and Tr. Nozaivae) they stretch 

 more or less into the lateral part outside the intestinal trunks (PI. 

 XXIII, fig. 1 ; PI. XXV, fig. 1). In Epibdella there is only a 

 single pair of testes of an irregularly ellipsoidal shape ; while in 

 Monocotyle the testes are three in number, of which two are situated 

 anteriorly and in a pair, and the remaining one posteriorly, with its 

 ■ anterior' end more or less wedged in between the former. In all the 

 other species the testes are very numerous, and are either rounded or 

 more or less polygonal in form according as they are more or. less 

 pressed against one another. Sometimes also they are lobed, as in 

 Tristomum ovale (PL XXIII, fig. 1). 



In most species the area occupied by the testes is entirely free 

 from all other organs, and the testes are situated midway between the 

 dorsal and the ventral side of the body. In Tristomum ovale, however, 

 the vitellarium, which in other species is confined to the lateral parts 

 of the body, extends into the central portion ; and the testes are here 

 situated quite on the ventral side, immediately inside the muscular 

 layer, leaving the whole dorsal side for the vitellarium (PI. XXIII, 

 fig. 7). 



