The length of the jointed flexible stems has been
taken from some entire stems in the collection of
Mr. Channing Pearce of Bradford, near Bath. Two
young individuals are attached to the calcareous
Pedicle or Base of the largest specimens. (Miller.)
Fig. 2. a. represents the remedial effect of calcareous
secretions in repairing an injury of the joints of the
stem. (Miller.)
Fig. 3. Pyriform Body of Apiocrinites rotundus, shewing
at its upper extremity the internal disposition of
the bones surrounding the cavity of the stomach.
(Original.)
Fig. 4. Vertical section of another pyriform Body, shewing
the cavity of the Stomach, and a series of lower
cavities, or hollow lenticular spaces, between the
central portions of the enlarged joints of the upper
portion of the vertebral column. Miller considers
these spaces as enlargements of the alimentary canal,
which descends through the axis of the entire column.
The surfaces of the joints of the vertebral column
are striated with rays, which articulate with corresponding
rays on the adjacent Plates, and allow of
flexure without risk of dislocation; locking into one
another nearly in the same manner as those figured
in PI. 49. Figs.' 5. 7. 9. (Original.)
Fig. 5. Restored figure of Apiocrinites, 30-Dactylus,
copied from Miller’s Crinoidea, Page, 96, PI. 1.
Fig. 2. (See V. 1. p. 429. Note.)
B. Base and fibres of attachment.
D, Auxiliary side Arms #. *
* These side arms afford a beautiful example o-f mechanical adaptations
and compensations, which are thus described by Mr. Miller
Fig. 6. Body of Apiocrinites 30-dactylus (Nave Encrinite
of Parkinson) copied from Miller’s Crinoidea, P. 98.
PI. 11. (See V. 1. p. 429. Note.)
Q. Pectoral Plates.
R. Capital Plates.
X. Orifice of the Mouth, or Proboscis, capable of elongation
for sucking in food.
Fig. 7. Another Body of a Nave Encrinite, drawn by Mr.
J. Sowerby from a specimen in the British Museum.
The same is Figured by Parkinson, in his Organic
Remains Vol. II. PI. XVII. Fig. 3. The lateral projections
are the commencement of the side arms.
This specimen has been corroded with acid, and consequently
has lost the superficial Corrugations and
in his admirable Monograph on Crinoidea, p. 97. “ The mechanism
of the joints of the side arms, where these insert into the column, is
well worthy of notice, particularly in old specimens. In the earlier
stage of their formation, the side arms being very short, and having
then little weight, a less firm mode of adhesion to the column than
becomes requisite at a subsequent period, being then sufficient, we
do not find more than one joint lodged in a socket, or concave impression
on the column; but when increase of size renders a stronger
support necessary, two or three succeeding joints of the side arms
become imbedded in this socket, (for which its extension as already
noticed allows room) and these joints instead of being arranged in a
series branching off at right angles from the column, become oblique,
their direction inclining upwards, so as to aid in bearing the additional
weight. The first joint of the side arms, where thus obliquely
inserted in the columnar socket, have that portion of their circumference
which is presented towards the upper part of the column
truncated, in such a curve as may fit them to the concavity of the
impression where they rest against it.
The surface of these joints, which fit into the columnar impression,
is smooth, being destined for adhesion only, but the articulating surface
between the contiguous joints, where motion also is to be allowed,
exhibits the usual mechanism of radiated ridges and furrows. These
joints are convex on the side nearest the column, and concave on that
most remote.”
G. II. G