188G.] MTTLE-KNOWN EARTHWORMS. 309 



and this character serves to distinguish the genus from Perichceta 

 in addition to those mentioned by Perrier. 



Between the 7th and 8th and "the 8th and 9th segments are the 

 orifices of the spermathecEe, which lie in the 8th and 9th segments 

 respectively ; the orifices are near to the ventral median line. On 

 the 12th segment anterior to the circle of setfB is the single median 

 aperture of the oviducts. 



On the 18lh segment are the paired apertures of the vasa de- 

 ferentia, which lie close together upon two slightly raised papillae ' 

 situated in an oval depressed area (see fig. 5, p. 310). 



Among rather more than 400 individuals I observed the following 

 varieties: — 



(1) The spermathecse were situated in segments 7 and 8; the 

 female generative pore was ui)on segment 1 1 ; the male generative 

 pores upon segment 16. The clitellum occupied segments 12-15 

 inclusive (fig. 3). 



(2j The female generative pores were two, one upon each of the 

 two segments 13 and 14 ; they were unpaired and median ; tlie male 

 generative pores occvipied the normal position upon segment 18. 



(3) The spermathecae were normal, viz. two pairs in 8 and 9. The 

 female generative pores were paired as in the last variety, and occupied 

 the same segments (viz. 13 and 14) ; the male pores were upon 

 segment 17. The clitellum extended from segments 13-17. 



(4) The female generative pores occupy segments 15 and 16 ; the 

 male pores are upon segment 20. 



(5) Of this variety there were two examples. In one the 

 spermathecae are normal, in segments 8 and 9. In both the female 

 pores are paired, but situated close to each other on the 14th segment ; 

 the male pores occupy the normal position upon the 18th segment. 

 In one specimen the clitellum extended from 13-17. 



(6) The spermathecse are present to the number of two pairs, but 

 are situated in segments 6 and 7 ; the single female generative pore 

 is upon segment 10. There are apparently three pairs of male 

 generative pores iipon segments 14, 15, and 16; only the two first 

 pairs were furnished with prostate glands ; the hinder pair therefore 

 are probably to be compared to genital papilla) (fig. 4). 



(7) The female pores are upon segments 15 and 16; the male 

 pores occupy the normal position upon segment 18. 



(8) The female pores are upon segments 14 and 15; the male 

 pores upon segment 18. 



(9) In this variety there are three pairs of spermathecse, occupying 



^ In a description of a new species of Pcrkmyx (P. machitoshii, Ann. & 

 Mag. Kat. Hist. 1883, xii. p. 217) I haye described the openings of the vasa de- 

 I'erentia as difi'ering from those of P. cxcavatits in being placed in an area which 

 is not depressed below the level of the surrounding integument. I find by an 

 examination of a large series of P. excavatui that this supposed specific dis- 

 tinction is probably due to the immaturity of the single specinaen of P. 7na<:in- 

 toshii; in immature examples of P. f.rctfii^to' the male genital appertures are 

 precisely as I have described them in P. macmtoMi. The latter species, 

 however, seems to me to be distinct on account of the structure of the prostate 

 glands and the thickened mesenteries of segments 6-9. 



