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PRANK E. BEDDARD. 
pointed out the presence of this sphincter, which Perrier 
was unable to definitely prove. Its presence is of course a 
point of similarity between the mucous gland and the more 
typical nephridia of the succeeding segments. 
The structure of the glandular tubules is compared by 
Perrier with that of nephridia, and he rightly points out their 
resemblance, abandoning his earlier belief (24) that these 
glands were a part of the alimentary system. At the same 
time Perrier does not consider that their homology with 
nephridia is definitely proved. 
It will be obvious from an inspection of PI. XXIII, fig. 1, of 
this paper that the structure of the mucous gland is identical 
with that of the nephridia. It consists of rows of perforated 
cells enveloped in a peritoneal sheath, which are so far abso- 
lutely indistinguishable from the nephridia of the remaining 
segments of the body. 
There is one point, however, to which Perrier has not 
directed attention in his memoir, and which conclusively 
proves that these mucous glands are nephridial ; that is, the 
presence of ccelomic funnels agreeing in their struc- 
ture with the funnels of the nephridia in the other 
segments of the body. 
The “ mucous glands occupy the first six segments, 
which contain no nephridia of the normal type ; these latter 
do not commence until after. It is therefore a matter 
of interest to inquire how far the “ mucous glands ” represent 
the missing nephridia. Do they, in fact, simply represent 
the hypertrophied first pair of nephridia, or are they formed 
by a fusion of all the nephridia typically present in the 
space which they occupy ? The fact that the external aper- 
tures are single would seem to prove the truth of the former 
supposition. On the other hand, the mucous gland does 
not only differ from the typical nephridium by its 
branched character, but also by the presence of 
several ccelomic funnels. 
In my preliminary notice (2) of the mucous gland I have, 
I now believe erroneously, stated that each gland has four or 
