DEVELOPMENT AND ANATOMY OF SOME EARTHWORMS. 29 
much as though there had been some confusion between 
nephridial tubule and blood-capillary, while fig. 7 hardly 
shows a continuity of nephridial tubule from segment to seg- 
ment. Further, both Beddard’s and Spencer’s figures, espe- 
cially the latter, clearly show that the tubules possess a different 
character in different regions, and that they are therefore much 
more specialised than the tubules of Pontobdella; and in no 
case can one be certain of the continuity of such fine tubules 
from an examination of sections alone. 
For my own part, (1) in spite of repeated and most careful 
search in preparations from so-called plectonephric worms made 
in all sorts of ways, I have never seen any connection between 
one nephridium and another in the adult. If, however, the 
mode of formation of the micronephridia is always such as I 
describe for Mahbenus, it is very possible that there are forms 
in which all or any of the micronephridia on the same side of 
any segment may remain connected together ; but I very much 
doubt whether there is ever any continuity from side to side or 
from segment to segment. 
(2) I have in a large worm like Mahbenus imperatrix 
been able to count the micronephridia belonging to a definite 
area, and then to mount the cuticle which showed a corre- 
sponding number of pores. 
(3) The micronephridia have always a complicated structure, 
similar to that of a meganephridium. This is the fact which 
first led me to doubt the plectonephric condition, and I have 
worked out with great trouble as much of the structure of a 
micronephridium as is shown in fig. 44, This nephridium 
belongs to Pericheta mirabilis. The micronephridia in 
this worm are very numerous, and have, or some of them at any 
rate have, funnels ; these funnels are not preseptal, and present 
eight marginal cells, ciliated on their centrally directed faces 
and arranged in a horseshoe fashion, and one central cell, but 
no other cells. The funnel is only 0°05 mm. in diameter. 
The coils of tubule are shown in the figure. Fig. 41 shows 
a similar complicated condition for Mahbenus, and I have 
obtained similar results in all the micronephridia which I 
