264 
FRANK E. BEDDARD. 
same time it appears to be certain that in the nephridia of 
these segments there is no longer an intimate connection 
between all the nephridial tubules of the same segment. An 
examination of a series of sections shows that there are tufts 
of tubules which are quite isolated from neighbouring tufts. 
On the other hand, there is — as has just been said — frequently 
no break between nephridial tufts of adjacent segments. These 
facts appear to me to be of some importance with regard to 
the views which I have elsewhere (1) advanced as to the origin 
of the Oligochset excretory system. We have here, as it appears 
to me, a commencing separation of the continuous excretory 
network into isolated nephridia. This breaking up has at first 
no relation to the segmentation of the body. The nephridial 
tufts have no regular arrangement within the segment, and 
their apertures are dotted about irregularly over its surface, 
and the separation into separate nephridia does not follow the 
lines of the intersegmental septa. The excretory system, 
in fact, appears to retain, longer than many other 
organs of the body, traces of the primitive unseg- 
mental condition. 
For the most part the nephridia of the posterior segments 
have the same appearance as those of the anterior segments, 
that is to say, they consist of tufts of tubules having an 
excessively fine bore. There are, however, tubules of greater 
calibre which appear to be wanting in the anterior segments. 
In this particular there is a resemblance between P. asper- 
gillum and Megascolides (Spencer). In that genus the 
posterior segments of the body contain nephridial tubules 
which are much larger than others in the same segments, and 
than all in the anterior segments of the body. There is also 
the further resemblance that the tufts of larger tubules are 
connected with funnels which project into the segment in front. 
In Perichaeta, however, the smaller nephridial tufts also 
possess funnels, which they apparently do not in Megascolides. 
Until the publication of Professor Spencer’s illustrated account 
of Megascolides it is impossible to say how far this resem- 
blance in the specialisation of the nephridia goes. The 
