Monthly Microscopical ; , a 
Journal, July 1, 1810. On Syncheta Mordaz. 27 
most restless among even that restless family. ‘Leydig complains 
of the incessant activity of H. senta—but Hydatina has flashes of 
repose, while Synchzta is perpetual motion itself. 
When it is swimming in ample space it turns endless somersets 
in a track regularly curved just like a corkscrew, varying this occa- 
sionally by swaying in semicircles from side to side like a skater : 
more rarely still it will lay hold of something with the forceps of its 
foot and then spin round its longer axis ; and once or twice I have 
seen it hovering in one spot like a fly over a flower, while its cilia were 
all the while lashing the water with a fury which rendered them 
under the dark field of illumination a mere halo round each lobe. 
All these varied motions would give the observer excellent op- 
portunities of studying its real shape were it not that they can only 
be watched in a large glass trough with a low hand magnifier. 
When once Synchxta is placed between two plates of glass in 
a drop of water sufficiently small to keep it within the field and 
tolerably within the focal length even of an inch objective, its cha- 
racteristic motions cease ; it swims incessantly round and across its 
prison, and at such a rate that the eye gets weary of following it. 
By gently compressing it one good view can be obtained, that of 
Fig. 1, but then it is always the same, or at all events can be only 
slightly altered by reversing the compressorium. In consequence 
of this no attempt has been hitherto made to describe the top of the 
head, or to delineate the front or side view. Its outline when swim- 
ming with either dorsal or ventral surface at right angles to the line 
of sight is that of a boy’s kite; and exactly where the kite’s tassels 
would be are two movable lobes fringed with a ring of powerful cilia, 
by means of which the creature performs its various antics in the 
water. Though the cause of ciliary action seems to be a mystery, 
yet the various ways in which the cilia of the lobes must work to 
produce Synchxta’s motions, admit, I think, of being explained. 
But I must first mention how after many abortive attempts I 
at last succeeded in obtaining a distinct view of the way in which 
the cilia are set on the side lobes as well as of the whole surface of the 
head. I had first thought that I might avail myself of its habit of 
occasionally adhering to the glass and then spinning round like a 
top, and I reduced the water it was in to a drop barely bigger than 
itself, and then gradually separated the glass plates of the compres- 
sorium so as to draw the drop out into a cylinder, hoping that the 
animal might thus be forced to stand up as it were on its tail and 
direct its head to the objective. With S. tremula this plan did 
actually once answer, and I saw an oval mouth and three red specks 
arranged one above and one on either side of the mouth: but with 
S. mordazx I failed completely ; it never ceased to turn somersets in 
the cylinder (though barely covered by it), and with such rapidity 
that observation was hopeless. Next, following a hint of Leydig’s, I 
