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ExPLANATION OF PLATE 47. 81
Fig. 6. Body of Apiocrinites 30-dactylus (Nave Encrinite of Parkinson) copied from Miller's Crinoidea, P. 98. Pl. 11. (See W. I. p. 323. 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. Pl. 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 Inost remote,
Tubercles which appear on the surface of Fig. 6. (Original.) X. Orifice of the Mouth.
Plate 48. V. I. p. 317.
Lily Encrinite, (Encrinites moniliformis,) from the Muschel-kalk, near Gottingen; in the Cabinet of the Marquis of
Plate 49. W. I. p. 318. Note.
All the Figures in this Plate except Fig. 3, are taken from the Petrefacten of Dr. Goldfuss, Pl. LIII. and Pl. LIV. They are so fully explained in our Vol. I. p. 317 and Notes, as to supersede the necessity of any further detailed description. Fig. 1. Restoration of the body and vertebral column of Encrinites moniliformis." Fig. 2. Base of attachment. Fig. 3. Portion of the summit of a vertebral column. (Original.) Fig. 4. Longitudinal section of Fig. 3. magnified. (See V. I. p. 319. Note.) Figs. 5, 7, 9. Joints from different parts of the vertebral column, showing the manner in which the articulating surfaces are crenulated to admit of flexure. Figs. 6, 8, 10. Vertical sections through the axis of Figs. 5, 7, 9, showing the forms of the internal cavity for the alimentary canal. 11–26. Profile and view of the articulating surfaces of joints, from various parts of the vertebral column.
(See W. I. p. 320. Note.)
EXPLANATION OF PLATE 50. 83
PLATE 50. V. I. p. 317, et seq.
Fig. 1. Fragment of the upper portion of Encrinites
moniliformis, showing the exterior of the Body, Arms, and Fingers, nearly closed around the ten
tacula. From a specimen belonging to Mr. Stokes. (Original.)
Fig. 2. Another fragment of the upper portion of the same species, reduced one-third, showing the summit of the column, the exterior of the body, arms, and fingers, and the manner in which the Tentacula are folded when the animal is closed. See W. I. p. 321. Note. (Copied from Parkinson's Organic Remains, Vol. 2. Pl. XIV. Fig. 1.)
Fig. 3. Side View of one finger, with its tentacula, (Goldfuss, Pl. LIV.)
Fig. 4. Interior of the body. See W. I. p. 322. Note. (Miller, P. 40. Pl. II.)
E. Pelvis + First Costal Plate # Second Costal Plate.
abdominal cavity. See V. I. p. 322. Note. (Copied
from Miller's Crinoidea, P. 41. Pl. III.)
PLATE 51. V. I. p. 326, and 330.
. 1. Pentacrinites Briareus, (nat. size) on a slab of
Lias from Lyme Regis, covered with a large group of the same animals, in the collection of the Geological Society of London. (Original.)
. 2. Rare and beautiful specimen of Briarean Penta
crinite, from the Lias at Lyme Regis, in the collection of Mr. Johnson, of Bristol, showing the plated integument of the abdominal cavity, terminated upwards by a flexible Proboscis, and surrounded by the commencement of the arms and fingers. This part of the animal is very seldom preserved. See V.I. p. 330. (Original.)
PLATE 52. V. I. p. 325.
1. Recent Pentacrinus Caput Medusae, from the bottom of the sea, near the I. Nevis, in the W. Indies, reduced from the Figure in Miller's Crinoidea, P. 48, Pl. I. In the front of this Figure, two of the arms with their hands and fingers are much smaller than the others, and show that these animals, when mutilated, have the power of reproducing lost parts.
D. Auxiliary side arms, articulating at distant intervals,
with the vertebral column; these also, when mutilated, are reproduced.
# First costal plate.
# Second costal plate.
ExPLANATION OF PLATE 52. - 85
Miller's description of this recent Type, of a family of which a few individuals only have hitherto been found, affords examples of many very delicate and beautiful mechanical contrivances, which throw important light on corresponding parts of the fossil species of this, and of kindred genera that abound in strata of the Secondary series, and more especially in the Lias. (See W. I. pp. 325. 326.328.) 2. Pentacrinus Europaeus, discovered in the Cove of Cork, and on other parts of the coasts of Ireland, by J. V. Thompson, Esq. (See W. I. p. 325.) In this figure several Individuals in different stages of developement, adhere by the base of an articulated column to the stem of a Coralline. 2. One of the Individuals magnified and fully expanded. See V. I. p. 326.
Mr. J. V. Thompson has more recently conjectured that the Pentacrinus Europaeus, which in early life is fixed by its stem to other bodies, is produced from the ovum of the Comatula, and becomes afterwards detached, and forms a perfect Comatula, capable of moving freely in the Ocean; at one time crawling amongst sub-marine Plants, at others floating, or swimming like Medusae. (See Proceedings of Royal Society, London, June, 1835.) 3. Small Briarean Pentacrinite, adhering to a fragment of Jet from the Lias at Lyme Regis. (See V. I. p. 329, Note.) 4. Fragment of the column of Pentacrinites subangularis. The Vertebrae are nicely articulated to admit of flexure without risk of dislocation. The uppermost joint d shows the lateral cavities for the articulation of auxiliary side arms. (Goldfuss. Pl. LII. f. g.) 5. Vertical Section of Fig. 4. In this Fig, and in