214 
Is Pedalion a Rotifer 1 
tail of the pseudopodium ; in Pterodina the pincers disappear and 
the tail ends in a ciliated cup ; while in Pedalion the tail disappears 
and the pincers are ciliated and set widely apart. 
These projections are of various shapes and most varied length, 
and Mr. Slack called my attention to the fact that in some speci- 
mens the cilia were invisible. I did not find this to be often the 
case in my specimens ; but I did meet with one or two in which I 
could not see the cilia. Possibly — as suggested by Mr. Slack — the 
cilia may at times cease to vibrate, and then lie close to the organ 
which carries them ; and possibly they may be shed by an animal 
which is not quite healthy. Indeed, I found one pair, on one 
of which there was only one cilium feebly lashing the water, and on 
the other but two stumps : there would be nothing unusual in this, 
as I have frequently seen Floscularia campanulata shake off the 
long setae which fringe its disk, and have seen the pieces float away. 
The cilia, too, on the trochal disk of dying rotifers come off on the 
slightest disturbance ; and Stephanoceros, when unhealthy, may be 
seen to throw off considerable portions of its fringed arms. 
Pedalion' s internal structure, as detailed above, closely resembles 
that of any one of the typical rotifers. If this be admitted, it must, 
I think, also be conceded that through some of its forms the class 
Eotifera is linked to the Crustacea rather than to the Annulata. 
"Who, looking at Pedalion’s pairs of jointed limbs worked by 
appropriate muscles, would think of placing it among the worms ? 
Gosse long ago insisted that the Eotifers must be ranked among 
the Arthropoda, adducing in evidence of this the approach of the 
manducatory apparatus to that of an insect ; the curious condition 
of the males, resembling that of the males of the Cirripedia ; and 
the presence of true condyles in the joints of such rotifers as T)ino- 
eharis and Polyarthra. To these three weighty reasons may now 
be added Pedalion s three pairs of legs ; and the effect of the whole 
is, I think, irresistible. 
In Dr. Eolleston’s ‘ Forms of Animal Life ’ it is stated that the 
sub-kingdom Vermes consists of animals “bilaterally symmetrical, 
very various in shape and other external characters, but agreeing 
in the absence of heteronomy from their post-cephalic regions, in 
not possessing hollow segmented limbs, and in having their loco- 
motor muscles closely connected with their integumentary system, 
not only on the ventral, but also on the dorsal and lateral aspect of 
their body walls.” 
Now, if the above is to be accepted as the definition of the sub- 
kingdom Vermes, then surely it excludes Pedalion: for Pedalion 
is strikingly heteronomous both as to its external shape and in- 
ternal organs, possesses six hollow limbs, and though its muscles are 
necessarily attached to the integument, yet they cannot be said to 
