1914.] J.Stephenson: Oligochaeta. 391 



The duct is equal or nearly equal in length to the ampulla, and is 

 swollen at its upper end, where it is delimited from the ampulla 

 by a deep constriction. The dilated portion of the duct contains 

 spermatozoa, and may thus be considered as a rudimentary 

 diverticulum. 



Perionyx koboensis, sp. nov. 



(PI. xxvi, fig. 12.) 



Numerous specimens ; in rotten wood, Kobo, Abor country, alt. 400 ft., 

 30-xi-iQii and 8-xiii-igii. 



Length 4 inches ; breadth 4 mm. ; colour, on the dorsal sur- 

 face dark purple anteriorly, more pinkish posteriorly, on the 

 ventral surface light gre^^ ; markedly iridescent on the dorsal sur- 

 face anteriorly. Segments 144. 



Prostomium epilobous ^. The rows of setae are implanted 

 on circular ridges, but there is lio other secondary annulation. 



The setal rings are almost complete, the mid-dorsal and mid- 

 ventral intervals corresponding to the omission of a single seta in 

 each case. The intervals between neighbouring setae are a little 

 wider on the dorsal than on the ventral surface. No setae are 

 specially enlarged. Numbers of setae : about 51/vii, about 49/xvii, 

 about 53/xxv, and 54 more posteriori}^ 



The first dorsal pore is in furrow %. 



The clitellum is represented only by a deeper shade of colour 

 on the dorsal surface of segments -J- xiii -xvi = 3-|-. 



The male pores are on xviii; near together, in the line of the 

 setae. They appear as small transversely situated sHts, in a 

 transversely elongated whitish field; this field is not raised beyond 

 the level of the setal ridge, of which it is a slight broadening, and 

 with which it is continuous at each side. There are no setae 

 between the male pores, which are separated by a distance equal 

 to about four intersetal intervals ; immediately lateral to the 

 male pores there is a space, equal to about three such intervals, 

 which is also destitute of setae The penial setae are described 

 below. 



The female pore is a minute transverse slit near the anterior 

 border of segment xiv. 



The spermathecal apertures are two pairs, in furrows f and § ; 

 they are minute pores, near the middle line, the distance between 

 the apertures of a pair being about equal to that between the 

 male pores. 



There is a slight thickening, of a whitish appearance, along the 

 anterior border of segment xix in the mid-ventral region ; I found 

 no other genital markings. 



Septa y, i, f , are sHghtly thickened. 



A gizzard is present in segment vi ; though its walls are 

 somewhat thickened it is nevertheless a distinctly rudimentary 

 structure. The oesophagus is narrow in vii, considerably bulged 



