34 E. NOMUKA : 



The next layer consists of very tall columnar cells with compact 

 cytoplasm and a nucleus at the base. The circular muscle layer 

 is very well, and the longitudinal layer less well, developed. The 

 outer peritoneum is like that of the body wall. 



When the ova have fully ripened or the clitellum has been com- 

 pleted, the boundary between the posterior portion of the lateral horn 

 and the transversal bridge vanishes and the former appears to open 

 directly into the latter. In this case the wall of the spermiducal 

 chamber becomes highly muscular and the roof of the median 

 chamber often bulges out at the male pore. 



Before leaving the sperm- duct I must go into a brief discussion 

 of the differences between Hatai's description and mine. Hatai 

 states that " it (the funnel) is continued into a slender duct, which, 

 after running on the inner side of the ovary till about the middle 

 of segment XI, curves toward the median plane slightly and opens 

 into the atrium. The latter has a spacious ellipsoidal cavity and 

 opens slightly in front of the setae directly into the common sperm- 

 duct chamber below the ventral cord, " From his figure 



and his statement that the vas deferens reaches to about the 

 middle of segment XI, his ' atrium ' may be easily identified with 

 my ' lateral horn ' of the spermiducal chamber and his ' common 

 sperm- duct chamber ' with my ' median chamber.' He says nothing 

 however about my ' atrium ' and the ascending and descending 

 portions of the sperm- duct. Further he says, " In immature indi- 

 viduals the atrium is followed by a slender duct-like portion, but 

 as the genital organs approach maturity the invagination of the 

 body wall becomes greater and the dorsal wall of the duct-like 

 portion is converted into the roof of the sperm- duct chamber, and 

 the atrium comes to open directly into the latter. Even in mature 

 specimens the sperm- duct chamber is sometimes very small and 

 the duct -like continuation of the atrium persists." From this it 



