X16 S. GOTO. 



nuclei, i. c, those whose nuclei have not met the section, are seen to 

 contain one or several vacuoles in their protoplasm (PI. XVI, fig. 5). 

 The top of each pilaster is seen in section to bear numerous cilia. As 

 we recede fi^om the ootyp, the pilasters become more and more flattened, 

 the cUia become longer, and the nuclei finally disappear altogether ; 

 but the pilasters are still separated by a shallow furrow, (PI. XVI, 

 fig. 6). As we recede still farther from the ootyp the piJaster« 

 finally disappear entirely, i. e., the protoplasmic reptmants of the original 

 epithelium have almost wholly disappeared, and the inner surface of 

 the uterine wall is covered uniformly with long, stout cilia (PI. XV, 

 fig. 10 ; PL XVIj.fig. 8). In this genus there is no genital atrium, 

 and the uterus consequently opens directly to the exterior by means of 

 a small pore (PL XVI, fig. 7). 



Monticelli'' thinks that in Oncliocotijle the terminal portion of 

 the uterus is specialised into an "ovidotto esterno"; but I think the 

 enlarged portion figured by Taschenberg is due to the eggs that 

 are contained therein. So far as I have observed there is in the Mono- 

 genea no specialised portion corresponding to Monticelli's "ovidotto 

 esterno." 



In most species of Tristomum the posterior end of the uterus is, as 

 already stated, enlarged into the shape of a funnel with its mouth 

 directed towards the ootyp, the front attenuated end of which 

 projects into it. It is usually of uiliform size throughout, the 

 rest of its extent ; but in Trist. sinuatum I have observed it 

 undergo another enlargetnent and then to be reduced to a nai-row canal 

 of uniform calibre (PL XXII, fig. 2). The w^all is in all cases formed 

 throughout of a thin, structureless membrane. In Trist. ovale and 

 Trist. rotundum the uterus operis directly to the exterior, close beside 

 the male genital opening (PL XXIII, fig. 8 ; PL XXIV, fig. 6) ; but 



1). Monticelli — Primo con tribute etc. p. 118. 



