8 Art. 4 -S. Ooto and H. Kikuchi : 



observable only when they are filled with secretion. The cells 

 are more or less pyriform and may measure 24// by 12//, or more. 

 The two intestinal cozca proceed on either side of the body further 

 backwards than the testis and then unite, and from this point a 

 very short median cœcum projects backwards. In the region of 

 the vagina the right cœcum is often reduced to a small tube in 

 sharp contrast to that of the other side. The intestinal cœca are 

 uniformly lined with cells which are all of one sort and cubical or 

 cylindrical, with distinct membrane around each but with a naked 

 free surface; the small vesicular nuclei are mostly situated near 

 the base of the cells and contain each a well stained dot-like 

 chromatin mass; the cytoplasm is more or less granular and 

 vacuolated and has but little affinity for haematoxylin. 



The nervous system presents nothing peculiar. The brain 

 lies just in front of the pharynx on the dorsal side of the 

 body and gives out nerves both anteriorly and posteriorly. Two 

 pairs of nerves are distributed to the anterior end of the body, one 

 just outside the inner pair of cephalic glands and the other more 

 laterally. Two pairs are also given out posteriorly, the large 

 ventral nerves arising from the posterolateral corner of the brain 

 and proceeding backwards on the ventral side just inside the 

 dermal musculature, along the inner border of the vitellarium, 

 and the smaller ventrolateral nerves arising from the brain 

 together with the former and running along the ventrolateral 

 region of the body. In the brain are embedded two pairs of 

 eyes, arranged in the four corners of a regular trapezoid, of which 

 the posterior side is the longest; the anterior pair is notably 

 smaller, and each eye consists of a pigment cup and a lenticular 

 body contained in it. 



The main vessels of the excretory system present an ar- 

 rangement that is generally characteristic of the Heterecotylea. 

 The excretory openings lie in a pair on either side on the 

 dorsolateral border of the body, about midway between the 

 pharynx and the paired yolk ducts. The terminal vessel is 

 comparatively large and proceeds inwards and slightly backwards 

 to the inner side of the intestinal cœca, where it divides into 



