88 



ESSENTIALS OF ZOOLOGY 



lip of the blastopore. The nephridia are developed like 

 protonephridia, but from a special ectodermal nephrogenous 



Jaw 



Denticles 



Tentacle 



Palp 



Prostomium 



Cirrus 



Eye. 



Peristome 



Parapodium 



FIG. 43. Head of Nereis diversicolor. 



Notopodium 



Dorsal ves. Dors. long. Dors. 



\ Int. mus. cirr. Chaeta 



Nerve cord Vent, 

 ves. 



Vent. I Aciculum\ 



: Neph. Vent, cirrus 



Neuropodium 



ties 



mus. 

 Parapod mus. 

 FIG. 44. Section of a segment of Nereis. (After Mclntosh.) 



band, and are converted into nephridia by developing an 

 opening into the coelom. As the body grows in length, which 



