36 Art. 2. — T. Kaburaki: 



that between the nioulli-opening and the posterior end of the body. 

 It leads into tlie narrow vestibnium, which receives from the front 

 the opening of the penis-sheath. Both the vestibnknii and the 

 penis-sheath are Uned with a single epithelium resting on a fine 

 basement membrane, beneath which he circular and longitudinal 

 muscular hiyers motlerately well developed. Eosinophil glands 

 occur all round the vestibulurn, into which they discharge them- 

 selves. 



The small testes numl)er about 18-22 on either side, lying 

 ventrally along both sides of the anterior gut trunk and extending 

 from the ovarian region to the -insertion of the pharynx. Each 

 testis is, as usual, a follicular body made up of sperm-mother-cells 

 and spermatozoa in several stages of development and surrounded 

 by the tunica propria. Ventrally each testis gives rise to a 

 short testicular canal which soon joins the vas deferens. The vasa 

 deferentia, which proceed backwards along the inner side of the 

 longitudinal nerve cords on the ventral side, gradually make an 

 inward bend, rising upwards at the same time, to open separately 

 into the seminal vesicle on the sides of the penis-bulb. The vas 

 deferens is filled with spermatozoa, but forming no peculiar en- 

 largement of the nature of accessory seminal vesicle. 



The penis consists of two parts, viz., the spherical bulbous part 

 of muscular nature and the free, conical intromittent part almost 

 horizontally disposed in the penis-sheath. The former part, being 

 distinguishable from the surrounding parenchyma with ease, is a 

 mass of the parenchyma traversed by several muscular fibres and 

 encloses a moderately wide cavity, the seminal vesicle the wall of 

 which is thrown into irregular folds. The lining epithelium is 

 made up of columnar cells resting upon a delicate basement mem- 

 brane. Posteriorly this cavity passes into the slender ejaculatory 

 duct which opens at the tip of the penis. In its course the ejacula- 

 tory duct makes two expansions, as seen in text fig. 11. In 

 structural respects the penis exhibits nothing peculiar, but the 

 muscular la3'ers of circular and longitudinal fibres, lying beneath 

 the external epithelium, are less developed than those found in 

 PL yonocephula and PI. v'lvida. Embedded in the parenchyma 



