Is Pedalion a Rotifer 1 
213 
sometimes not an Lour. They are shown in Figs. 3 ami 4, of 
their proper relative size, swimming round their mother. 
Starting from somewhere on or under the intestine, and at its 
posterior extremity, are the two usual convoluted tubes (Fig. 1, h). 
Each of these has one ordinary bunch of loops at (k), with two 
vibratile tags just above it, and another bunch at (l), close under 
the eye, with a third vibratile tag close adjoining. 
This system of tubes and tags is most difficult to see in Peda- 
lion; not only are the lower portions of the tubes unusually trans- 
parent and unusually free from loops and tags, but the upper por- 
tions, where alone are the loops and tags, are hidden generally 
behind a stout striated muscle running from near the eye to the 
outer limb, and the muscle itself has frequently in front of it some 
portion of the curved and folded surfaces of the same limb. 
Under these circumstances, it is needless to say that the tags 
and loops are not to be seen ; and these unfavourable conditions are 
often aggravated by the stomach’s being so distended as to form a 
coarse shifting yellow background to every portion of the field of 
view. It was not till I had nearly exhausted my stock of rotifers 
that I caught sight of the vibratile tags again this year ; but since 
then I have repeatedly traced the tubes from end to end on several 
sjtecimens. 
Pedalion has a nerve mass (Fig. 1, m) closely applied to the 
buccal funnel, with two eyes (clear spheres on plates of red pig- 
ment) seated on it, and with nerve threads connecting it to the 
ganglionic intumescences of the dorsal and shoulder antennae ( n , o). 
In all these respects it closely resembles Triarthra ; and a some- 
what similar nervous system is visible in most of the free-swimming 
rotifers. There are also two delicate threads, commencing at the aper- 
ture of the oviduct, but whose other ends I have been unable to find. 
I may here point out a curious and persistent difference between 
the free-swimming rotifers and the tube-forming ones. Most of 
these latter — Melicerta, Limnias, and CEcistes, for example — have 
their antennae on the ventral surface, just below the ciliated chin, 
which underlies the mouth: but the free-swimmers have their 
antennae on the dorsal surface, the normal number appearing to be 
three ; one on the mid- dorsal line at the neck, and either two at the 
sides, as in Triarthra , Hydatina, and Asjolanchna, or two at the 
posterior extremity, as in Byncheeta. 
The ciliated projections at the posterior extremity of Pedalion 
seem at first sight as abnormal as its six limbs : but as they exude 
a viscid secretion I have little doubt that they represent the 
“ pincers ” of Brachionus, Synchseta, and others, none of which 
“ pinch,” but all of which secrete a web by which the animal moves 
itself at will. In Brachionus the “pincers” are at the end of the 
