48 
POPULAR SCIENCE REVIEW. 
sometimes with all at once. One in my possession, from a 
perfect condition, so shortened all the arms (not, however, while 
under my eye), that they were reduced to the merest rudiments 
or tubercles, retaining a few of the pencils of setae ; and though 
these subsequently lengthened a very little, they did not become 
normal again. 
Of an individual which I had found in health, the foot, 
the next day, separated itself from its attachment by the 
sloughing’ of a portion, leaving a ragged edge. The body did 
not withdraw from the case. The foot went on to dissolve away 
upwards, in a very ragged form : about the third day the arms 
became shrunken, flat, and distorted. The setae were now seen 
to be of great length; they vibrated still when jarred, and now 
and then spontaneously. Under these circumstances the nature 
of the vibration was far more discernible than in health. I 
could now distinctly see that each seta bent laterally, and then 
straightened itself like a whip smacked; the flexion was per- 
formed suddenly, the extension gradually. The flexion appeared 
to be from south to west.* 
The animal is not difficult to keep alive in jars of fresh water, 
exposed to the light, but guarded, of course, from the hottest 
rays of the sun. The water-plants on which it lives attached 
are essential; but these need not be rooted. Fragments of 
Myriophyllum, Geratophyllmn, Nitella, Potamogeton, &c., maybe 
detached, and will continue to live and grow while submerged. 
I have kept Steplianoceros for five or six weeks. 
I do not know any other localities in the British Isles for the 
species than those which I have mentioned. But it is widely 
spread on the continent. Eichhorn found it at Dantzig, exactly 
a century ago, and figured it in 1775. Ehrenberg rediscovered 
it near Berlin in 1831, and afterwards saw it on several occasions. 
Weisse met with it once at St. Petersburg. Perty’s Stepha.no- 
ceros glacial Is, found by him in Switzerland (in the Todtensee, 
on the Grrimselliohe), was probably only a deformed and diseased 
specimen of S. Eichhornii. 
Such is the history, so far as I have unravelled it, of the 
largest, the rarest, and the most elegant species of the class 
Botipera. An exquisite form it is, and one whose structure 
* I use this mode of indicating circular motion, because it is precise : we 
have only to suppose the plane of the circle to be horizontal, and no mistake 
can possibly be made. The ordinary phrase, “ from left to right,” or vice versa, 
is indefinite and ambiguous, because “ right” and “ left” are opposite points of a 
circle, and motion from one to the other may be in opposite directions. If to 
describe the sun’s apparent motion as “ from left to right” is intelligible with 
us, it is only because a portion of the circle is beneath the horizon. At the 
poles it would be finite ambiguous. 
