gear On Synchxta Mordax. 29 
each lobe. When Synchexta seizes any support with its pincers it 
has only to cause these ciliary waves to run both from left to right, 
or vice versa (the cilia at the same time striking a little obliquely 
in the same direction), to cause its whole body to spin in the oppo- 
site direction round its longer axis. Generally the ciliary waves 
run in opposite directions and so neutralize the tendency that each 
set has to turn the animal round its own length. 
The ciliated lobes are employed solely for the purposes of loco- 
motion, but the ciliated rings (Fig. 2, a, a) on the ventral surface, 
and the interrupted row (Fig. 2, b) on the dorsal surface, are used to 
bring food to the neighbourhood of the mouth (Fig. 2, ¢), which I 
believe is also fringed with fine cilia, though of this I am not quite 
certain. The ciliated rings (Figs. 2, a, and 4, d) are mounted on cup- 
like protuberances, the edges of which can be depressed or erected 
at the will of the animal, so as to cause vortices on either side of it 
as well as in front: this is effected by muscles attached to several 
lobes on which the cups rest. 
On the centre of the head are two projections (Fig. 1, a) bear- 
ing sete arranged like a fan, and each of the rings (which are 
omitted in Fig. 1 for the sake of distinctness) surrounds a papilla 
(Fig. 2) bearing sete. The use of these contrivances is easily seen 
in the living animal; for whenever any prey approaches the mouth 
the “horns” (as Ehrenberg calls them) and the sete on the papillee 
are bent towards each other and over the mouth, so as to prevent the 
escape of anything that has been brought by the action of the rings 
to the mouth. This function of the sete (as Mr. Cubitt has pointed 
out) is common to all rotifers; and it may be best seen in some of 
the Brachionxa, in which the sete are habitually arranged in dome- 
fashion over the buccal funnel. 
S. mordaz’s head carries also four bundles of seta, which are, I 
believe, organs of touch. Each is mounted on a short piston to the 
end of which a muscle is attached, and each can be protruded or 
partially withdrawn through its own papilla. The hairs in each 
bundle often move very rapidly, sometimes all curving over in the 
same direction like a horse’s tail, at others all spread out in different 
directions like a feather-brush ; but such motions are I believe in- 
voluntary, and are due to the currents caused by the cilia. I have 
not yet exhausted the tactile apparatus of Syncheta. Its dorsal 
surface rises in a hump which carries on its vertex in a depression 
another bunch of sete (Figs. 2, d, and 4,a). This is really a double 
bunch (Figs. 5, and 4,6); each springing from the same rocket- 
shaped contrivance which I have figured in Hydatina, Triarthra, 
and S. tremula; and the long ends of which are probably nerve 
fibres connecting the setze with the nervous mass in the head. These 
organs in Triarthra longiseta have been independently observed and 
figured by Dr. H. Grenacher, who has given a good drawing of the 
