COE : NEMERTEANS OF WEST AND NORTHWEST COASTS. 



19 



Piinnett (: 01*') has found a very similar condition in INIicrella, 

 and both these authors agree that the anus is situated dorsally to 

 the base of the caudal cirrus, while Bergendal (:02*, p. 47) was 

 inclined to the opinion that the anus is situated ventrally in Val- 

 ENCiNURA, although his sections did not allow him to determine this 

 point mth certainty. 



Alimentary Canal. 



In all nemerteans the alimentary canal consists of a single, more 

 or less distinctly ciliated tube extending practically the whole length 



Fig. 5. — Carlnella frenata. Transverse section of body in region of nephridio- 

 pores, showing cavity of stomacli (s^) and enlarged blind sac of rhynchocoel 

 {re') with smaller, posterior chamber of rhynchocoel (re) above it ; nd, efferent 

 nephridial iluct. ^ 



of the body. The mouth is small and situated subterminally on the 

 tip of the snout in the Hoplonemertea, where it opens with or near 

 the rhynchodaeum. In the other orders it is of larger size, often an 

 elongated slit, and is situated posterior to the brain commissures. 

 Only in the genus Cephalotiirix is it placed far behind the brain. 

 The anus usually opens dorsally at or near the posterior extremity of 

 the body. 



