270 
FRANK E. BEDDARD. 
A. Nepbridia forming a network, 
consisting of excessively fine 
canals, continuous from seg- 
ment to segment. 
( 1 ) ? 
(2) Nephridial network of pos- 
terior segments, partly com- 
posed of tubules of greater 
calibre. Numerous ccelomic 
funnels. Pericbseta asper- 
gillum. 
(3) Larger nephridial tubules in- 
creased in size and forming a 
nephridium nearly independent 
of the finer tubes, and opening 
by a single ccelomic funnel. 
P. armata, Megascolides. 
B. Nepbridia forming a network con- 
sisting of wider canals, discon- 
tinuous at the septa. 
(1) No further specialisation. 
Deinodrilus .' 
(2) Nephridial network, partly 
composed of tubules of greater 
calibre. Numerous ccelomic 
funnels. Acantbodrilus 
multiporus. 
(3) Nephridial network of pos- 
terior segments, chiefly com- 
posed of larger tubules, open- 
ing by a single ccelomic funnel. 
Dicbogaster. 
The nephridia of Acantbodrilus multiporus, of Dicho- 
gaster, and of Deinodrilus, are formed of tubules which, 
as said, are on the whole of greater calibre than those of 
Perichseta. The measurements may be approximately de- 
termined by a comparison of figs. 11-14. At the same time 
the nephridia of these types present other differences from 
Pe rich set a. The network is much reduced in extent and 
in two ways. First, only a limited area of each segment 
is occupied by the nephridia. They are by no means so 
abundantly developed as in Perichseta, not nearly so 
abundantly developed as in the anterior segments ofPericheeta 
aspergillum. Secondly, the intercommunication from 
segment to segment has disappeared in Acantbodrilus aud 
Dichogaster, and has almost disappeared in Deinodrilus. 
In the last-mentioned genus the nephridia are attached to the 
anterior wall of their segment, and are, for the most part, 
entirely restricted to this situation. In one or two instances, 
however, a small tuft of tubules was attached to the posterior 
wall of a segment and in these cases (which are not at all 
1 Tbe apparent absence of ccelomic funnels in this genus may perhaps be a 
secondary modification. 
