Though the paired arrangement of the nephridia is the prevalent one in the Chaetopoda, there are many examples, among the Oligochaeta, of species and genera in which there are several, even many, nephridia in each segment of the body, which may or may not be connected among themselves, but have in any case separate orifices on to the exterior.
In terrestrial A, Lumbricus : 9, to, segments contain ing spermathecae, the orifices of forms dorsal pores are usuwhich are indicated; 14, segment b ally present; in aquatic earing oviducal pores; 15, segforms a head pore only.
B Acanthodrilus: cp, orifices of sperminal, rarely dorsal, at a math ecae;, oviducal pores; little distance from end male pores; on 17th and 19th of body.
6, d), which were originally described by Lankester as orifices possibly connected with the evacuation of the generative products.
On account of their position they were termed by him the " capito-pedal orifices," being placed near the junction of head and foot.