1892.] SPECIES OF EARTHWORMS. 703 



16. Ilyogenia africana, nov. gen., n. sp. 



Among the specimens of Eudriloides durbanensis was an example 

 of a totally different species — a fact which I only recognized after 

 examining longitudinal sections of the head end of the worm ; the 

 smalluess of size, absence of pigment, and similarity in the position 

 of the clitellum prevented me from distinguishing them when alive. 

 They belong, however, to totally different families ; the species now 

 to be described is a Geoscolecid. 



It has paired setae which show no recognizable ornamentation. 

 I did not observe whether those upon the clitellum were in any way 

 different from the rest. 



The clitellum commences in the xiith segment and ends in the 

 xixth ; it is a little diflBcult to be precise about the actual beginning 

 and ending. If we reckon as clitellum only that tract of epidermis 

 where the " untere " and " obere Saiilenregion " of Claparede can 

 be recognized, then the clitellum begins at the commencement of 

 segment xiii. ; but the epidermis covering segment xii. dorsally differs 

 from that lying in front by the fact that the glands are elongated 

 and very darkly stained ; they are indeed the exact counterpart of 

 the elitellar gland-cells in many aquatic Oligochaeta whicli I have 

 examined when prepared in a similar fashion. These deeply 

 staining cells contrast in that very particular with the clear and very 

 faintly stained gland-cells of the segment in front. The clitellum is 

 " saddle-shaped." The nephridia are paired structures ; the first 

 pair are situated in segment iii. The funnels have the usual position 

 and are not large. The nephridia themselves are without the 

 terminal muscular duct ; I observed the plexus formed by the "fine 

 tubes " of the nephridium to which Benham has called attention in 

 Microchceta. The external orifice of the nephridium is in front of 

 the ventral setae; those belonging to segment ix. open just behind 

 but quite independently of the spermatothecae. From the eighth 

 segment, but more distinctly from the ninth, the nephridia are 

 invested by a thick sheath of clear pyriform cells with deeply 

 staining nuclei ; the cells themselves are not much staiued. These 

 cells, which cover the nephridia, are sometimes quite clear but more 

 often have a vacuolate appearance. 



The alimentary canal presents the usual divisions ; there is, 

 however, no trace at all of a gizzard — not even the slightly thickened 

 tract of muscle which marks a portion of tiie oesophagus in Ponto- 

 drilus. The pharynx commences in the second segment, the brain 

 lying rather behind the transverse furrow which separates it from 

 the buccal cavity, and therefore near to the posterior boundary of 

 segment ii. The pharynx appears to occupy the third segment 

 and a part of the fourth ; as usual, numerous retractor muscles are 

 inserted into its dorsal wall. Masses of septal glands occupy the 

 fourth to the seventh segment ; those of the last segment are very 

 much smaller ; the masses of unicellular glands of successive seg- 

 ments are connected by fibrous strands which pass through the 

 septa. The oesophagus passes straight back to the twelfth segment, 

 where it opens into the intestine. It is nowhere ciliated, except just 



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