188G.] LITTLE-KNOWN EARTHWORMS. 299 



Bendrolana, &c.), there have been described more species of Per/c/i«/a 

 than of any other genus. Ratlier more than thirty have been named, 

 but several of these, as Dr. Ilorst ' has pointed out, are merely 

 synonyms, while a large number have evidently been too imperfectly 

 characterized to admit of recognition. In the majority of cases the 

 number of the spermathecse and the absence or presence of variously 

 formed diverticula have proved useful as specific characters ; but 

 species have been distinguished on other grounds which happen to 

 agree in the number and form of the spermathecse. The presence 

 of genital papillae is almost universal in the genus Perichceta, and 

 these are jjlaced either in the neighbourhood of the spermathecse or 

 of the reproductive apertures ; this character serves to differentiate 

 P. indiea from P, affinis, which otherwise agree pretty closely in 

 structure. I have had the opportunity of examining a number of 

 specimens of both these species as well as of an apparently new 

 species which is closely allied to both. A few notes therefore, which 

 will perhaps serve more clearly to define these species, may be worth 

 adding to what is known about them. 



Of Pc7'ich(eta indiea I have received about half a dozen specimens 

 from New Caledonia though the kindness of Mr. E. L. Layard, C.M.G. 

 The specimens were of varying size, the largest individuals reaching 

 a length of some 6 inches. Their colour (in alcohol) was a very 

 dark brown, with an indistinct whitish hue in the middle of each 

 segment, marking the insertion of the setae. The latter are 

 remarkable for the fact that one or m.ore on either side of the ventral 

 median line are very much larger than the rest : this fact has already 

 been noted by Horst (Nederl. Arch. &c. loc. cit.), and a similar 

 variation in the size of the setse occurs in Perrier's species P. luzonica 

 and P. liserialis \ The two last-mentioned Perichcetce have up to the 

 present been but briefly described ; but the description is sufficient 

 to show that they cannot be confounded with P. indiea. P. biserialis 

 has only two pairs of spermathecse and several pairs of genital 

 papillse in the segments following the 18th, while there are four pairs 

 of spermathecae in P. indiea. Jn P. luzonica the clitellum occupies 

 four segments. Dr. Ilorst mentions two pairs of genital papillae 

 j)laced respectively upon segments 7 and 8 ; in one of my specimens 

 there were three pairs, the third pair being upon segment 6. 

 Another important variation is in the number of segments which 

 compose the clitellum : in most of the individuals where the clitellum 

 was developed, it was found to occupy segments 14-16 inclusive, as 

 described by Horst for this species and as commonly found in the 

 genus. In one specimen, however, the clitellum was a segment 

 short, being developed only upon the 1 4th and 1.5th rings; the 

 clitellum was fully developed upon these segments and sharply 

 defined, as it usually is in this genus. It is of some importance to 

 note this fact, since a species of Perichata, P. bicineta, has been 

 characterized mainly on account of the restriction of the clitellum 

 to two segments. 



' Notes from the Leyden Museum, vol. v. p. 18fi. 

 ^ Comptes Eeiidus, t. Ixxxi. (1875) p. 2044. 



20* 



