34 s. GOTO. 



of the body iDut 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 Octocotijle described in this paper 

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

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

 rows. In soi]ie other species also, as in Onchocotijh and most species 

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

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

 behind the ovar}^ In most species again, they occupy the median 

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

 some species of Trist oiimm (2V. ovale and Tr. No.uuvae) they stretch 

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

 XXIII, fig. 1 ; V\. XXY, fig. 1). In EpMcUa there is only a 

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

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

 anteriorly and in a pair, and tlie 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 hjbed, as in 

 Tristominn ovale (PI. XXIII, tig. 1). 



In most species the area occupied l)y 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 Tridomum. ovale, however, 

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

 of the body, extends into tlie central porti(3n ; 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). 



