Japanese Tricladida Maricola. 21 



by means of the digestive tract. However, the life and growth of 

 the worm piece lacking either the mouth or the pharynx seem to 

 me to suggest that it can breath with the whole extent of the 

 ^skin. 



Excretory System. 



(3f the excretory canals I have been able to obtain no more 

 insight than a few loops at some |)()ints in the dorso-lateral parts 

 of body. So far as my 'observations go, the system in Pr. lactea 

 appears to exhibit an arrangement that is generally characteristic 

 of Pt'ocerodes. Dorsally there exist two main vessels on either 

 side of tho body which are directly connected with one another by 

 means of anastomosis, thus presenting an irregular network. The 

 main vessels send out at various points numerous ducts generally 

 perpendicular to the surface, which open to the exterior at be- 

 tween the epidermal cells. Generally an epithelium seems to be 

 present in the ducts, but in some cases the wall is not sharply 

 differentiated from the surrounding parenchyma. In sections I 

 have seen no evidence of a definite epithlium. 



Nervous System. 



The nervous system of tlie species, upon which my observa- 

 tion w^as based, agrees in the main parts with that of other 

 Triclads and is represented by the central parts consisting of the 

 brain and the longitudinal trunks as well as by the peripheral 

 part. 



Each longitudinal nerve trunk gradually widens anteriorly 

 and passes over a brain mass, those of both sides being con- 

 nected by a number of strong commissures. So far as I have 

 examined, the morphological point of distinction between both 

 the central parts could not be ascertained with ease, but it seems 

 probable that ' ' die Abzweigungsstelle der sog. vorderen Längs- 

 nerven " presents such a point, as pointed out by Böhmkt. 

 The brain has the same appearance as that of other Triclads, but 



