NEREIS VIRENS SARS 



99 



tudinal muscles form- 

 ing two dorsal and two 

 ventral longitudinal 

 bands, and oblique 

 muscles running from 

 the sides of the dorsal 

 surface to the middle 

 of the ventral surface. 

 The innermost layer 

 of the body wall is 

 formed by the parietal 

 layer of the peritoneal 

 epithelium. 



The ccelome o r 

 body cavity is the 

 space between the 

 body wall and the ali- 

 mentary canal. It is 



FIG. 21. --Circulatory 

 system of Nereis vircns, 

 side view, after Turnbull. 

 DB, dorsal blood vessel; 

 V, recurrent blood vessel 

 connecting dorsal blood 

 vessel with U network; U, 

 network on pharynx (pro- 

 boscis); SG, salivary gland; 

 E, branch to the oesopha- 

 gus; D, dorsal vessel to 

 parapodium; C, lateral 

 connecting vessels; K, ten- 

 tacular blood vessel; G, 

 network; S, branch from 

 ventral vessel to G net- 

 work; T, vessel connecting 

 ventral blood vessel with 

 U network; F, ventral ves- 

 sel to parapodium; VB, 

 ventral blood vessel; L, 

 anterior portion of ventral 

 blood vessel; PR, phar- 

 yngeal ring vessel, 



K 



G 



