IV 



VEEMESNEPHRIDIA 



245 



Tf- 



nt 



canals like the embryonic head nephridia of the Annulatu, which issue 

 between mouth and anus 

 into the so - called vesti- 

 bulum. The JBrachiopoda 

 (Fig. 150, p. 226) possess 

 one pair, less frequently 

 (Rhynchonella) two pairs 

 like those permanent ne- 

 phridia which in the Polij- 

 chceta, Sipunculida', and 

 Phoronis discharge the 

 sexual products. They 

 emerge to the right and 

 left of the mouth into the 

 mantle cavity. 



Rotatoria and Dino- 

 philus. DinophUus gyro- k 

 ciliatns (Fig. 162) possesses 

 five pairs of nephridia, In 

 which show a remarkable 

 agreement with the provi- 

 sional trunk nephridia of 

 certain Poluchceta (Nerei* 

 ctiltrifei'd, Fig. 159, p. 239). 

 They lie one behind the 

 other in the trunk region 

 in those segments which 

 are outwardly indicated 

 and demarcated by ciliated 

 rings. The nephridia of 

 the Rotatoria (Fig. 161) 

 consist of two looped, and 

 in certain places much con- 

 voluted canals, which run 

 longitudinally near the 

 intestine ; these open 

 into the cloaca, generally 

 forming a contractile 

 terminal vesicle. The 

 longitudinal canals usually 

 have short accessory 



branches whose ends FIG. 161. Organisation of Hydatina senta, after Plate. 

 , ... j ' i i -i -i w, Wheel organ ; ni, nephridial ciliated cells ; n, nephridia ; 



^ClliateCl lODCS, Vioratlle ph, pharynx; md, gastric glands; m, stomach; ds, vit> !- 



larium ; l;s, germarium ; rb, outline of the contractile vesicle ; 



ed, hind-gut ; u, uterus ; a, anus ; fd, cement or pedal glands ; 



It, lateral feeler ; ?>i, nerve of the same ; c, advanced egg. 



organs) seem to be con- 

 structed like the ends of 

 the water-vascular system 

 of the Plat odes, and of 



the embryonic head nephridia of the 



