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exterior by a small oval aperture situated just above and 
behind the dorsal end of the neuropodium (fourth to 
ninth). 
Immediately behind the posterior part of the funnel 
there is a small pinkish ovoid, club-shaped or cylindrical 
mass of cells. This is one of the reproductive organs of 
the worm, an ovary or testis as the case may be. There 
is no gonad on the first nephridium. 
The funnel and anterior part of the excretory portion 
of the organ are attached to the body wall by a thin 
mesentery, and the funnel is further held in its place by 
one of the oblique muscles which crosses it and is fused 
to it. 
The nephrostomes of the first pair of nephridia are 
situated on the anterior face of the third diaphragm. 
They are somewhat smaller than those of succeeding 
nephridia (fig. 27). The first and last pairs of nephridia 
are subject to considerable variation, and the former 
especially are often appreciably smaller than any of the 
succeeding nephridia. Out of about 160 specimens ex- 
amined eight were found in which there is some departure 
from the normal condition. Six of these specimens 
show reduction or Joss of the first nephridium. In one 
example the first nephridium of each side is very small, 
its secreting portion being only as thick as an ordinary 
pin; in the second example the first left nephridium is 
normal but the right one has no funnel; in the third case 
the first nephridium on each side has no funnel; in the 
fourth and fifth examples the first nephridium of one side 
has a very small funnel while the corresponding one of the 
other side is represented by a funnel only; and in the 
sixth specimen the first left nephridium is totally sup- 
pressed, the corresponding right one being present, but 
without funnel. In the other two cases of variation the 
