THE GIANT EARTH-WORM OF GIPPSLAND. A7 
(Megascolides) in which highly-developed nephridia, with internal openings, are only 
_ present in the posterior region of the body. If the hypothesis with which we started 
be correct, viz., that the Pericheta and the Acanthodrilus are primitive forms, so far 
as their nephridial system is concerned, it follows that in these forms, and hence 
presumably in all Terricole, the genital ducts have no connection with the nephridia, 
and are not to be regarded as nephridia specially modified to serve the purpose of 
conveying genital products to the exterior. A nephridium, before it can function as a 
genital duct, must have an internal ciliated funnel, and in Pericheta and 
Acanthodrilus the nephridia have not reached this stage of development, and yet 
genital ducts are present, which not only have internal openings, but differ in 
important respects histologically from the nephridia. The relationship of the 
openings of the ducts to the setze, or the absence of such arrangement, can by itself 
be regarded as evidence of but slight value, and yet it is really the only direct 
evidence, if such it can be considered, in favour of a connection between the two sets 
of structures. It is perfectly possible that the same causes which have apparently 
operated, with the result that a relationship often exists between the nephridial 
openings and the setz, operated quite independently to produce the same result in the 
case of the genital ducts. 
Further investigations, especially with regard to the development of the genital 
ducts, may, if for example it could be proved that the nephridial system of P. 
aspergillum, Megascolides, &c., are degenerate, give some clue to the homologies 
of the genital ducts. At the present time our knowledge seems to indicate that in 
earth-worms an homology does not exist between these and the nephridia. 
