EXPLANATION OF PLATES 



PLATE I. 



Fig. i. Pericliaeta indica. 



Dissected, sp, spermathecae ; g, gizzard ; sp s, sperm-sac ; dv, dorsal vessel ; nph, nephridia ; 

 sp gl, spermiducal gland ; caec, caeca. 



Fig. 2. Perichaeta everetti. 

 Ventral view of anterior segments, sp, spermathecal pores ; ? oviducal pore ; c? male pores. 



Fig. 3. Polytoreulus magileiisis. 

 Ventral view of anterior segments. <J male pore ; sp p, pore of spermathecal sac. 



Fig. 4. Octochaetus multiporus. 



Dissected slightly from the side, gl, peptonephridium ; g, gizzard ; nph, nephridia ; dv, dorsal 

 vessel ; sp gl, spermiducal glands ; n, nerve-cord ; v v, ventral blood-vessel. 



Fig. 5. Perichaeta posthnma. 

 Ventral view of worm ; ? oviducal pore ; < male pores; p, genital papillae. 



Fig. 6. Libyodrilus violaceus. 

 sp p, spermathecal pore ; male pore. 



Fig. 7. Eudrilus eugeniae. 

 $ female pore : <$ male pore. 



PLATES II AND III. 



Generative organs of various types of Oligochaeta diagrammatically represented. The male 

 organs are coloured pink, the female blue. To all the figures the following lettering applies: 

 T, testes ; F, sperm-duct funnels ; sp s, sperm-sacs ; o, ovary ; od, oviduct ; e s, egg-sacs ; os, sper- 

 mathecal sac ; sp, spermathecae ; sp gl, spermidncal gland. 



PLATE IV. 



Fig. i. Libyodrilus. 



Dissection, o, orifice of spermathecal sac; sj)s, sperm-sacs; sp gl. spermiducal glands; 

 vv, ventral blood-vessel ; dv, dorsal blood-vessel ; n, nephridia. 



Fig. 2. SipJionogaster millsoni. 



Tr, penial (?) processes. 



The remaining figures bear a legend. In all of them the following is the significance of the 

 letters : g, gizzard ; ca, calciferous glands ; sp, spermathecae ; sp s, sperm-sacs ; h, ' heart ' ; sp gl, 

 spermiducal glands ; vd, vas deferens ; od, oviduct. 



The clitellar segments are numbered ; the dorsal vessel with its branches are coloured red. 



