Japanese Freshwater Triclads. 7 



ing a large surface. Embedded in the parenchyma directly around 

 the penis are numerous eosinophil penis-glands, which make their 

 way into the cavity. 



The paired ovary is placed between the third and fourth pairs 

 of the lateral branches of the anterior gut trunk. It is a small 

 spherical body, showing egg-cells in several stages of development. 



Tlie vitelline glands are represented by branched cellular 

 cords with cells arranged in single or double rows. They are ex- 

 tensively distributed almost throughout in the interstices between 

 the gut diverticulae and connected with the oviduct at numerous 

 points. However, the mode of connexion coukl not be made out 

 clearly. The vitelline cell is of small size and contains an almost 

 spherical nucleus, which is far larger than that of the surrounding 

 tissues and exhibits a closer affinity for haematoxylin. 



The oviduct of each side springs from the postero-lateral 

 surface of the ovary as an ampullaceous passage, tilled with sper- 

 matozoa, which soon assumes the character of a narrow duct, 

 proceeding straight backwards just along the outer side of the 

 longitudinal nerve cord. In the region of the genital opening it 

 suddenly bends inwards, at the same time rising upwards, to unite 

 with its fellow of the opposite side into a short conimon duct, which 

 curves backwards and downwards to open into the vestibular part 

 of the atriimi from above. (J)n one occasion there was observed a 

 curious complete loop of the oviduct, occurring on the right side 

 at ihe atrial region. The oviduct exhibits a distinct lumen 

 throughout the entire length. With the exception of the unpaired 

 terminal duct the direct wall is composed of a ciliated epithelium, 

 which shows no nuclei at all. The nucleus-containing parts of the 

 epithelium are suidv into the surrounding parenchyma, as recorded 

 by several investigators to be the case in Planar ia g onocephala, PI- 

 polychroa, PI. burmaennls., Dendrocoelum lacteum, etc. Innnediately 

 exterior to the layer mentioned, come two layers of internal circular 

 and external longitudinal muscular fibres, surrounded by a number 

 of cells which probably represent the sunken parts of the epithe- 

 lium. Processes from the cells are occasionally found to extend 

 to. and to join, the epithelium. In the unpaired terminal part of 



