APPEXDICULATUA OF JAPANESE WATERS. 17 



The length of triink in the only specimen I have obtained 

 measured 1049 n and that of tail 3148 fi. 



0. Oihopleurn rufcscens Fol (1872). 



PL lY., figs. 1-G. 



Buccal gland and Eisen's oikoplast well developed. 

 Lefts tomach without a l)lind sac. Right stomach with 

 a small nipple-shaped blind-sac at its lower middle 

 portion. Intestine very short; rectum vertically 



standing. Atrial cavity very long and its outer aper- 

 ture shifted nearly to the posterior margin of stomach. 

 Genital glands do not cover tlie lateral side of alimen- 

 tary canal; ovar^^ single and thick; testis paired. Tail 

 with slender muscular coating and with one sub- 

 chordal cell. 



The dor,-;al side of tlie trunk strongly curves upward over 

 the œsophagus, so that, when the genital glands are well 

 developed, there is formed a deep notch on the dorsum. 



The oikoplast epithelium covers nearly the entire alimentary 

 canal. The epithelial cells of the lateral oikoplast zone are round- 

 ish and all of a similar size (fig. 1, PL IV.). The buccal gland is 

 large and spherical. The Eisen's oikoplast is remarkably well 

 developed. The endostyle is short and its posterior extremity is 

 widely separated from the anal papilla and the spiracle. The 

 branchial cavity is narjow. The atrial canal is very long, its 

 outer aperture lying near to the posterior margin of stomach. 



The left stomach is circular and has at its posterior and 



