STRUCTURE OF UROCHiETA AND DICHOGASTER. 
239 
five funnels. In several instances I have good reason to 
believe that there are only three present. The funnels are of 
considerable size, and apparently of a somewhat horse-shoe- 
shaped form ; hence in a continuous series of sections it is not 
difficult to mistake one funnel for two contiguous but separate 
funnels. The three funnels of each mucous gland are, how- 
ever, so widely separated that no mistake of that kind could be 
made. At the same time I do not wish to state positively that 
there are only three present; and for the matter of that, the 
exact number does not appear to me to be of great importance 
unless it could be proved that each branch opens into the 
coelom by a funnel. I shall presently show reasons for be- 
lieving that this is not the case. Now, two of these funnels 
are situated at the distal extremity of the gland and correspond 
in their position to the fourth segment ; the third funnel is 
more anterior in position and corresponds to the fifth 
segment, so far as one can judge in the absence of definite 
septa separating these segments. Although there is some 
appearance of correspondence to the segments in the arrange- 
ment of the ciliated funnels, yet it must be admitted that the 
ciliated funnels are not arranged in a regular, meta- 
meric fashion. Taking into consideration the facts (to be 
referred to more at length below) that the nephridia of some 
of the posterior segments are furnished with more than a 
single funnel, and the extent of the first pair of nephridia 
(“ tubiparous glands”) of certain Polycliseta sedentaria, 
it is perhaps more likely that the mucous glands represent the 
nephridia of the first segment alone ; on the other hand, there 
is nothing in the facts, as I read them, which is contrary to 
the supposition that the mucous gland represents the nephridia 
of all the segments which it occupies, and that the primitive 
condition is only shown, and that imperfectly, in the disposi- 
tion of the ciliated funnels ; the concentration of this portion 
of the nephridial system being due to its specialised function. 
Then again, there is a third alternative. Supposing that the 
mucous gland is the nephridium of the first segment alone, is 
its branching to be considered as a remnant of what I have 
