1915.] J. STEPHENSON : Indian Oligochaeta. 65 
Remarks.—This species is interesting, since it seems to show stages in the transi- 
tion from the meganephric to the micronephric condition, and from the tubular to 
the branched prostate. 
The micronephridia are here not scattered over the septa or body-wall, but arise 
as a single tuft from the ventral end of the meganephridia in the posterior part of the 
body, as if constituting a branched proliferation of the originally single nephridium.! 
Anteriorly the main portion of the nephridium has disappeared, leaving only the 
branching tuft. The micronephridial condition has been evolved more than once 
within the family Megascolecidae, and possibly therefore in different ways on different 
occasions. The above may represent one mode of origin; further evolution along 
this line might consist in the dissolution of the tuft and the scattering of the indivi- 
dual branches on the body-wall. The genus Tvinephrus may represent another mode; 
here three such tufts may have appeared before the disappearances of the main portion 
of the original nephridium. 
It is interesting to note that a number of micronephridial genera of the Mega- 
scolecidae (e.g. Notoscolex, Megascolex, Pheretima, Lampito, other species of Mega- 
scolides (21), as well as Eutyphoeus of the subfamily Octochaetinae) regularly present 
the tufted condition, and the attachment by a narrow stalk, in one or more of the 
anterior segments; these tufts, just behind the pharynx, in segments v and vi or 
thereabouts, are conspicuous in the ordinary dissection of the worms. Comparison 
with the tufted condition which exists in the present species would suggest that 
these ‘‘ pharyngeal tufts’’ also are proliferations from the ventral end of a now 
vanished meganephridium, though the diffused micronephridia on the septa and 
body-wall may quite possibly have originated otherwise. 
With regard to the prostates, these must be designated as tubular. At the same 
time the slight indentation of the margin, and the presence of branches of the main 
tube in the interior of the gland, seem to show a passage towards the lobed or 
branched condition of Notoscolex, Megascolex, Pheretima, etc. If Michaelsen is right 
in supposing that the branched prostate has arisen only once in the history of the 
Megascolecidae, the present form would presumably be placed somewhere near the 
main line of descent of the above genera. 
Megascolides duodecimalis, sp. nov. 
(Plate VII, figs. 10-11.) 
Parambikulam, 1700-3200 ft., Cochin State; 16—24-xi-1914 (F. H. Gravely). A single specimen. 
External characters.—Length 160 mm., diameter 5 mm.; colour a dirty grey, 
somewhat mottled, lighter at the anterior end. Segments ca. 317; segments v and 
vi biannular, most or all of the subsequent ones triannular ; vii, viii, ix indistinctly 
quadriannular dorsally. 
Prostomium invisible. 
' Michaelsen however (9, pp. 200, 202) would derive such tufts from the aggregation of originally 
scattered micronephric villi, 
