Philosophical transactions, Vol. L. Part II. For the year 1758.: Giving some account of the present undertakings, studies, and labours, of the ingenious, in many considerable parts of the world.Various
History
Philosophical transactions, Vol. L. Part II. For the year 1758.: Giving some account of the present undertakings, studies, and labours, of the ingenious, in many considerable parts of the world.
Various
Science -- Periodicals
In the drawing [_See_ TAB. XXIX. _Fig._ 1.] is shewn the anterior part
of this animal, which has much the appearance of a Star-fish. Here
are eight arms about three inches in length, united at their roots,
and placed circularly at equal distances in the same plane, which has
a considerable sinking towards the center. These arms diminish from
their rise to their extremities, and end exceedingly small. Near the
head they are quadrilateral, but the under-side contracting gradually
to an edge, they become towards the ends trilateral. On the upper side
of each arm are two rows of _acetabula_, or suckers, standing in a
beautiful order, as close as they can well be placed, and beginning
from the center of all the arms. These suckers are perfectly circular,
with edges flat on the top, and a round cavity in the middle of each.
They are largest in the widest part of the arm, and lessen as the arm
diminishes, till they become so small as hardly to be discernable. It
is very difficult to tell their number: I counted as far as fifty in a
row, but am certain there are many more; and I don’t imagine the eight
arms have so few as a thousand on them. They rise some height above the
surface of the skin; and wherever they are not, the skin of the arms
(unless on the under-side) is granulated like shagreen[160].
As in the other kinds of Polypi the mouth is placed between the arms
conspicuously enough, I expected to find it so in this; but the spirits
had contracted it so much, that I could discern no opening at all
where I thought the mouth must be; and therefore could not say, with
assurance, that the mouth was placed there. Under this difficulty
I applied to Sir Hans Sloane’s most valuable collection of natural
history in the British Musæum, where I found several species of this
kind of Polypi, and amongst the rest a small dried specimen of the same
species as ours, and a much larger one in spirits, of a species that
comes very near it.
This large specimen afforded the information I stood in need of: for
though here also the mouth was closed, and the beak drawn down into
the center between the arms, so as not to be seen at all; yet, by the
help of Dr. Morton and Mr. Empson, I had the satisfaction to see the
mouth opened, and the beak in the same situation, and of the same form
and substance, as in the other kinds of Polypi. Having gained this
knowledge, by applying the point of a bodkin, I easily felt the beak
in our Polypus; but in so small a subject it cannot be brought to view
without dissection, which is the reason it does not appear in these
drawings.
_Fig. 2._ represents the Polypus so placed as to shew the situation of
the eyes and the form of its body, and also in what manner the arms
are turned back in the specimen before us; but we may suppose them
thus disposed merely in the act of dying, and that when alive they are
moveable in all directions.
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