436 OLIGOCHAETA 



to each spermiducal pore ; these setae, however, do not form an irregular group ; they 

 are arranged in a line which is perfectly continuous with the line of setae on the rest 

 of the segment. These setae have a more marked ornamentation than the setae of 

 surrounding segments ; as in many Geoscolicidae, the remaining setae of the body 

 show, here and there at all events, an ornamentation ; the presence of these genital setae 

 was first pointed out by MICHAELSEN (13) ; I showed later that they existed in 

 P. excavatus as well as in P. gruenewaldi; in the two other species of the genus 

 which are at all adequately known there are no specially modified setae in the 

 neighbourhood of the male pores ; such setae as there are do not differ in any marked 

 way from the ordinary setae of the body. The close approximation of the two male 

 pores is also seen in the case of the spermathecal orifices ; the spermathecae themselves 

 are, except in P. sultans and P. sansibaricus, two pairs only ; in six species, viz. 

 P. gruenewaldi, P. violaceus, P. sansibaricus, P. arboricola, P. saltans, and P. inter- 

 media, the Bpermathecae have diverticula which are (more usually) small and 

 sessile upon the duct of the spermathecae ; in P. macintoshii there is a diverticulum 

 even more rudimentary ; I have not found a diverticulum in P. excavatus, and it is 

 stated by ROSA to be missing. There are eight species of the genus, which is confined 

 to the tropics of the Old World. 



(i) Perionyx excavatus, PERRIER. 



P. excavatus, PERKIER, Nouv. Arch. Mus., 1872, p. 126. 

 Megascolex excavatus, VAILLANT, Armeies, p. 69. 



Definition. Length, nomm.; breadth, 4mm.; number of segments, 165. Colour (in spirit) 

 purplish on dorsal surface, yellow beneath ; clitellum yellowish brown. Cliielhim, 

 XIII (XIV) XVII. Setae, 25-50 in number per segment. Male pores on two papillae, 

 which are enclosed in an area ; on either side of each a row of about five longer penial setae. 

 Gizzard very slight in VII. A pair of calciferous glands in XIII. Intestine begins in 

 XVII. Last pair of hearts in XII. Hab. India; Luzon. 



This is the type-species of the genus ; the chief mark of distinction between 

 this and other species is in the form of the papillae which bear the male pores, 

 and in the genital setae which accompany these orifices. The male pores are each 

 placed upon a semicircular elevation, the two being in close contact. These flat 

 papillae are both depressed below the surface of the surrounding integument, the 

 depression being marked anteriorly and posteriorly, but not laterally, by grooves. 

 Not only the setae of the eighteenth segment are modified, but those of neighbouring 

 segments, particularly the nineteenth, to some extent. 



