14 ART. 5. T. AIDA. 



4. Oikopleiira 'tnicrostoniaf iiov. sp. 

 PI. II., figs. 1-5. 



Buccal gland wanting. Eisen's oikoplast present. 

 Blind-sac of the left stomach large and finger-like, 

 ascending upward along the j^osterior wall of œsopha- 

 gus. Spiracle widely separated from the posterior end 

 of endostyle. Genital glands cover the lateral side of 

 alimentary canal; testis paired; ovary unpaired and 

 fiat. Tail with broad musculature, w^ithout subchordal 

 cells. 



This species resembles Oik. longicauda in the form of ali- 

 mentary canal and reproductive organs, but is distinguished by 

 possessing Eisen's oikoplast, by the absence of hood, by the larger 

 size of the epithelial cells of the lateral oikoplast and by the wide 

 interspace between the endostyle and the spiracle. 



The oikoplast epithelium extends over the anterior half of 

 the alimentary canal. The Eisen's oikoplast is very small and 

 is composed of t\vo oblong cells. The epithelial cells of the lateral 

 oikoplast zone are large (fig. 1, PI. IL). 



The mouth is very small and the branchial cavity is narrow. 

 The atrial canal is narrow and short. The spiracle is widely 

 removed from the endostyle and the anal opening. The left lobe 

 of stomach has a large finger-shaped blind-sac, which as- 

 cends along the posterior side of the œsophagus. The right lobe 

 is nearly equal to the left in size and is connected with the latter 

 by its whole breadth. The gigantic glandular cells of stomach 

 are found at the bottom of the left lobe in a single row ; three 



