igoS.] W. MïCHAEivSKN : Oligochœta of the Indian Empire and Ceylon. 153 



FAM. MEGASCOLECID^. 



Sub-fam, Megascolecinas. 



In the definition of the genera of this great sub-family I maintain in general the 

 views I published lately in connection with my descriptions of the Oligochsetes from 

 South- Western Australia.' The following pages contain only one change or rather 

 elaboration of the system. I separate from the large genus Megascolex with a micro- 

 nephric condition of the excretory system, those species in which there is found a pair 

 of meganephridia besides the micronephridia in the segments of the middle and pos- 

 terior parts of the body. We formerly knew only one species with such a nephridial 

 system, i.e., Lampito mauritii, KINB. ( ^Perichceta armata, BEDD.), and in my former 

 systematic discussions I did not lay any stress upon the deviation of this species. As 

 I now have had occasion to study two more species of the kind, I think it necessary 

 to separate this group from Megascolex. This separation does not alter the verbal 

 definition of the genus Megascolex; but, owing to the use of the term "micronephric," 

 we must bear in mind that this definition no longer includes a reference to the con- 

 dition characteristic of Lampito mauritii. The new group separated from Megascolex 

 must be called genus Lampito, KINB. (see below). 



GEN. PLUTEIvLUS. 



Pl.UTEI.IvUS INDICUS, M1CHI.SN. 



(Plate xiii, fig. 9.) 



P. i., MICHAELSEN, in Mt. Mus. Hamburg, xxiv, p. 148. 



Present four half mature specimens, one of which represents a variety. 



External Characters. — Dimensions : Length 60 — no mm., greatest thick- 

 ness 2| — 3 mm., number of segments ca. 160. 



Colour uniformly grey or brownish grey. 



Head indistinctly epilobous, if not tanylobous. 



Setse widely paired till nearly separated. At the anterior part of the body the 

 pairs equal about a half (the variety) or a third part (typical form) of the median 

 ventral distance and about f of the middle lateral distances (anteriorly aa=2 — ^ab, 

 ah = j\, hc = cd or aa : ab : be : cd=^ — 6 : 2 : 3 : 2). Just behind the clitellar region 

 the pairs get distinctly narrower (postclitellar aa = ^ — ^ab, ab = 2bc = cd or aa : ab: 

 be: c^ = 3 — 4 : i : 2 : i). Towards the posterior end the pairs grow wider, finally 

 almost equalling the middle lateral distances and in the variety getting near the median 

 ventral distance (at the hinder end aa = \ — 2ab, ab, be and cd differing only a little, 

 ab<bc>cd). The median dorsal distance is in general smaller than half the circum- 

 ference of the body, at the anterior part of the body only a little, at the hinder part 

 very much {dd<^ u); at the hinder end it is only 3^ times (typical form) or even not 



1 W. MICHAELSEN, Oligoctiseta, in Die Fauna Südwest- Australians, etc., Hamburg, 1907, i, p. 

 149, £E. 



