ON A NEW ENTEROPNEUST FROM MISAKI. 



83 



in the abdominal region, they remain as only a thickening of the 

 ciliated epithelium at the bottom of the grooves finding in the dorso- 

 lateral angles of the gut wall ; circular muscle layer makes its appearance 

 just external to the longitudinal muscle fibres standing on the gut wall 

 of the anal region 1 (Fig. 4, cm/.) ; pygochord dilates slightly along its 

 distal margin (Fig. 4, peli.) 



Nervous system : — Splanchnic nerve fibre layer is well developed in 

 the buccal and pharyngeal walls ; the lumen of collar nerve-cord dis- 

 continuous ; roots two solid and directed posterio-dorsally. 



Vascular system : — at the anterior portion of the proboscis wall, 

 dermal capillaris makes four longitudinal stems, each lies respectively on 

 the sagittal median and mid-frontal planes ; ventral and dorsal medial 



Horizontal section passing through 

 the dorsal portion of the collar and the 

 genital pleurae showing the circular ves- 

 sel at the anterior portion of the trunk. 



c. collar-ccelom, co» circid;ir vessel, g. 

 gonad, /. trunk-ccelom. 



Fig. 6. 



Transverse (slightly oblique) section through the anterior 

 portion of the genital region showing the communication of the 

 lateral vessel with the dorsal vessel and the capillaries of the gut 

 wall. 



do. dorsal vessel, g. gonad, gc. gut cavity. If. lateral septum, lo. 

 lateral pbc. post-brafichial canal. 



1. ) This muscle fibres do not make a complete ring around the gut canal but inter- 

 rupted by the pygochord. 



2. ) This arrangement of the dermal capillaries gives us a characteristic appearance in 

 the cross sections though the proboscis-tip of this species. 



