24 



E. NOMUIIA : 



a strong longitudinal (? sub- intestinal) vessel comes to view on the 

 left side of the intestine as a part of the intestinal vascular layer ; 

 the position is in my opinion due to distortion. 



4). The integumentary networks lie in the peritoneum of the 

 body wall and are connected with the main trunks by paired dorsal 

 and ventral integumentary vessels. 



a. The dorsal integumentary vessels branch out always pairwise 

 from the longitudinal dorsal vessel just in front of the posterior 

 septum of segments I — X, but in the segments posterior to the twelfth 

 the initial parts of a pair unite more or less to form an unpaired 

 vessel. 



In segment I (fig. 19), each vessel branches out pairwise from 

 the dorsal vessel near the setal zone of segment II and after 

 running dorso-laterally for a short way 

 divides into two, of which one runs 

 straight laterally to the body wall while 

 the other proceeds obliquely anteriorly 

 into the prostomium and the anterior 

 region of the first segment, passing over 

 the dorsal side of the brain. 



In segment II also the dorsal in- 

 tegumentary vessels run straight laterally 

 near the setal zone of segment III from 

 the dorsal vessel to the body wall. 



In the segments behind the third 

 each dorsal integumentary vessel has one 

 or more constrictions in its course, with 

 unicellular valves like those of the dorsal 

 vessel. 



In segments III-V, the dorsal integumentary vessels are not 

 large and always proceed laterally from their constricted starting 



Fig. 19. 



Blood-vessels of the anterior 

 part of the body ; from a living 

 specimen, x 100. bw — body wall, 

 d.v — dorsal vessel, v.v — ventral 

 vessel. 



