IV 



VERMES NEPHRIDIA 



245 



nt 



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

 between mouth and anus rc ~ 



into the so - called vesti- 

 bulum. The Brachiopoda 

 (Fig. 150, p. 226) possess 

 one pair, less frequently 

 (Rhynchonella) two pairs 

 like those permanent ne- 

 phridia which in the Poly- 

 chceta, Sipunculidce, and 

 Phoronis discharge the 

 sexual products. They 

 emerge to the right and 

 left of the mouth into the 

 mantle cavity. 



Rotatoria and Dino- 

 philus. Dinophilus gyro- 

 ciliatus(Fig. 162) possesses 

 five pairs of nephridia, In 

 which show a remarkable 

 agreement with the provi- 

 sional trunk nephridia of 

 certain Polyclmta (Nereis 

 cuUrifera, 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 Rotatvrici (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 

 hrflnrhps whosp ends FlG< ^--Organisation of Hydatina senta, after Plate. 

 j 11^ -1 -i ro ' Wheel or an ; nt > ne P Mdial ciliated cells 5 n > nephridia ; 



(ciliated lobes, Vlbratlle P h, pharynx ; md, gastric glands ; m, stomach ; ds, vitel- 

 Seem tO be COn- l aruim ; fcs, germarium ; c&, outline of the contractile vesicle; 

 li'l^-P thp PTirk of ^. hind -S ut ;. uterus ; a . anus ;/^ cementor P edal S 1 ands; 

 Ui It, lateral feeler ; In, nerve of the same ; e, advanced egg. 



the water-vascular system 



of the Platodes, and of the embryonic head nephridia of the 



