On Dissotrema papillatuin. 13 



region of the prepharyngeal windings the dorsal and ventral 

 portions pass into each other without any break. There are two 

 principal yolk ducts running longitudinally on each side of the 

 body, one for the dorsal vitellarium, the other for the ventral. 

 They are very distinct near the hind end of the vitellarium, 

 whence they proceed backwards and unite at about the level of 

 the ovary and form the paired yolk ducts. These turn towards 

 the median line of the body, passing on its way between 

 the Laurer's canal and the seminal receptacle on the dorsal side 

 and the seminal vesicle on the ventral, and unite to form 

 the yolk reservoir, from which a short unpaired yolk duct 

 leads forwards to the oviduct, into which it opens directly 

 before the ootype. As to the structure of the walls of the 

 female ducts, the following may be added: the oviduct has a syn- 

 cytial wall with very few scattered nuclei, surrounded by a layer 

 of fine circular muscle fibres, which form a sphincter at either end 

 of the insemination chamber ; the seminal receptacle has also a 

 similar wall surrounded by an inner layer of circular and an outer 

 of longitudinal fibres; the ootype is provided with an epithelial 

 wall whose cell boundaries are not apparent, followed by an inner 

 circular muscle and an outer longitudinal of exceedingly fine 

 fibres; the uterus has an epithelial wall, whose cells are closely in 

 contact with one another at their bases and project free into the 

 lumen, the muscular coat consisting of inner circular and outer 

 longitudinal fibres, the latter few in number; the wall of the me- 

 traterm is cuticular like that of the genital atrium and has the 

 same muscle layers as the uterus. The Laurer's canal and the 

 yolk ducts appear to be entirely destitute of a muscular coat. 



About the parenchyma we want to note the presence of sub- 

 cuticular cell groups and of lymph spaces. The former are arranged 

 in some parts at nearly regular intervals a short distance away 

 from the cuticle, and each group consists of a few to some dozen 

 relatively small cells with a compact nucleus and an apparently 

 homogeneous or finely granular cytoplasm, both staining well 

 with hematoxylin. They are probably of glandular nature 



