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him, through his highly philosophical analysis of the structure of this curious family of fossil animals.*
From the details I have thus selected from the best authorities, with a view to illustrate the most important parts that enter into the organization of the family of Encrinites, it is obvious that similar investigations might be carried to an almost endless extent by examining the peculiarities of each part throughout their numerous species. We may judge of the degree, to which the individuals of these species multiplied among the first inhabitants of the sea, from the countless myriads of their petrified remains which fill so many Limestone beds of the Transition Formations, and compose vast strata of Entrochal marble, extending over large tracts of country in Northern Europe and North America. The substance of this marble is often almost as entirely made up of the petrified bones of Encrinites, as a corn-rick is composed of straws. Man applies it to construct his palace and adorn his sepulchre, but there are few who know, and fewer still who duly appreciate the surprising fact, that much of this marble is composed of the skeletons of millions of organized beings, once endowed with life, and susceptible of enjoyment, which after performing the part that was for a while assigned to them in living nature, have contributed their remains towards the composition of the mountain masses of the earth.*
* Our PI. 47 gives Mr. Miller's restoration of two other genera, fig. 1, the Apiocrinites rotundus, or Pear Encrinite, with its root or base of attachment, and its arms expanded. Fig. 2 is the same with its arms contracted. Two young individuals and the broken stumps of two other small specimens, are seen fixed by their base to the root of the larger specimens, showing the manner in which these roots are found attached to the upper surface of the great oolite at Bradford near Bath. When living, their roots were confluent, and formed a thin pavement at this place over the bottom of the sea, from which their stems and branches rose into a thick submarine forest, composed of these beautiful Zoophytes. The stems and bodies are occasionally found united, as in their living state; the arms and fingers have almost always been separated, but their dislocated fragments still remain, covering the pavement of roots that overspreads the surface of the subjacent Oolitic limestone rock.
This bed of beautiful remains has been buried by a thick stratum of clay. Fig. 3 represents the exterior of the body, and the upper columnar joints of this animal, about two-thirds of the natural size. Fig. 4 is a longitudinal section of the same, showing the cavity for the viscera, and also the large open spaces for the reception of nourishment between the uppermost enlarged joints of the column.
At fig. 5 we have the Actinocrinites 30-dactylus, from the corboniferous limestone near Bristol. D. represents the auxiliary side-arms which are attached to the column of this species, and B its base and fibres of attachment. Fig. 6 represents its body, from which the fingers are removed, showing the pectoral plates, Q, and capital plates, 11, which form an integument over the abdominal cavity of the body, and terminate in a mouth (x,) capable of being protruded into an elongated proboscis by the contraction of its plated integument. Fig. 7 represents the body of an Encrinite in the British Museum, figured by Parkinson, vol. 2, fol. 17, fig. 3, by the name of Nave Encrinite. The mouth of this specimen also is seen at X, and between the mouth and the bases of the arms, the series of plates which form the upper and exterior integuments of th» stomach.
Of more than thirty species of Crino-fdeans that prevailed to such enormous extent in the Transition period, nearly all became extinct before the deposition of the Lias, and only one presents the angular column of the Pentacrinite; with this one exception, pentangular columns first began to abound among the Crinoideans at the commencement of the Lias, and have from thence extended onwards into our present seas. Their several species and even genera are also limited in their extent; e. g. the great Lily Encrinite (E. moniliformis) is peculiar to the Muschelkalk/and the Pear Encrinite to the middle region of the Oolitic formation.
The Physiological history of the family of Encrinites is very important; their species were numerous among the most ancient orders of created beings, and in this early state their construction exhibits at least an equal if not a higher degree of perfection than is retained in the existing Pentacrinites; and although the place, which, as Zoophytes, they occupied in the animal kingdom, was low, yet they were constructed with a perfect adaptation to that low estate, and in this primeval perfection they afford another example at variance with the doctrine of the progression of animal life from simple rudiments through a series of gradually improving and more perfect forms, to its fullest development in existing species. Thus, a comparison of one of the early forms of the Genus Pentacrinite, viz. the Briarean Pentacrinite of the Lias, (PI. 51 and PI. 52, Fig. 2. and PI. 53) with the fossil species of more recent formations, and with the existing Pentacrinus Caput Medusae from the Caribbean Sea, PI. 52, Fig. 1, shows in the organization of this very ancient species an equal degree of perfection, and a more elaborate combination of analogous organs, than occur in any other fossil species of more recent date, or in its living representative.
* Fragments of Encrinites are also dispersed irregularly throughout all the depositions of this period, intermixed with the remains of other contemporary marine animals.
The history of these fossil bodies, that abound in the lower strata of the Oolite formation, and especially in the Lias, has been much illustrated by the discovery of two living forms of the same Genus, viz. the Pentacrinus Caput Medusae,* (PI. 52, Fig. 1,) and Pentacrinus Europaeus, PI. 52, Figs. 2, 2'. Of the first of these a few specimens only have been brought up from the bottom of deep seas in the West Indies; having their lower extremities broken, as if torn from a firm attachment to the bottom. The Pentacrinus Europaeusf (see PI. 52, Figs. 2. 2',) is found attached to various kinds of Sertularia and Flustracea in the Cove of Cork, and other parts of the coast of Ireland.
* See Miller's Crinoldea, p. 45.
t See Memoir on Pentacrinus Europseus by T. V. Thompson, Esq. Cork, 1827. He has subsequently ascertained that this animal is the young of the Comatula.
It appears that Pentacrinites are allied to the existing family of star-fishes, and approach most nearly to the Comatula; (See Miller's Crinoidea, PL 1, and p. 127:) the bony skeleton constitutes by far the largest portion of these animals. In the living species this bony framework is invested with a gelatinous membrane, accompanied by a muscular system, regulating the movements of every bone. Although, in the fossil species, these softer parts have perished, yet an apparatus for muscular attachment exists on each individual bone.*
The calcareous joints which compose the fingers of the P. Europaeus, together with their tentacula, are capable of contraction and expansion in every direction; at one time spreading outwards, like the Petals of an open flower (PI. 52, Fig. 2,) and at another rolled inwards over the mouth, like an unexpanded bud; the office of these organs is to seize and convey to the mouth its destined food. Thus the habits of living animals illustrate the movements and manner of life of the numerous extinct fossil members of this great family, and afford an example of the validity of the mode of argument, to which we are obliged to have recourse in the consideration of extinct species of organic remains. 'In this process we argue backwards, and from the mechanical arrangements that pervade the solid portions of fossil skeletons, infer the nature and functions of the muscles by which motion was imparted to each bone.
I shall select from the many fossil species of the Genus Pentacrinite, that, which from the extraordinary number of auxiliary side-arms, placed along its column, has been called the Briarean Pentacrinite, and of which our figures (PI. 51. Figs. 1, 2; PI. 52. Fig. 3.; and PI. 53.) will give a more accurate idea than can be conveyed by verbal descriptions.*
* See the tuberclee and corrugations on the surfeces of the bones engraved at PI. 52, Figs. 7, 9, 11,13, 14, 15, 16, 17.
The upper part of the vertebral column of Pentacrinites is constructed on principles analogous to those already described in the upper part of the column, of the Encrinite.f
All the joints of the column, when seen transversely,
present various modifications of pentagonal star-like forms;
hence their name of Asteriae, or star-stones.
These transverse surfaces are variously covered with a \
* PI. 51 represents a single specimen of Briarean Pentacrinite, which stands in high relief upon the surface of a slab of Lias, from Lyme Regis, almost entirely made up of a mass of other individuals of the same species. The arms and fingers are considerably expanded towards the position they would assume in searching for food. The side-arms remain attached to the upper portion only of the vertebral column.
At PI. 53. Fig. 1 and 2 represent two other specimens of the same species, rising in beautiful relief from a slab, which is composed of a congeries of fragments of similar individuals. The columns of these specimens, Fig. ii, a, show the side-arms rising in their natural position from the grooves between the angular projections of the Pentagonal stem. At PI. 52, Fig. 1.
F. F. are seen the costal plates surrounding the cavity of the body; at H
the Scapula;, with the arms and fingers proceeding from them to the extremities of the tentacula,
At PI. 53. Fig. 3. exhibits the side-arms rising from the lower part of a vertebral column, and entirely covering it. Fig. 4. is another column, on which, the side-arms being removed, we see the grooves wherein they articulated with the alternate vertebrae. Fig. 5. exhibits a portion of another column slightly contorted.
j The columnar joints of the Briarean Pentacrinite are disposed in pieces alternately thicker and thinner, with a third and still thinner joint interposed between every one of them. PI. 53. Figs. 8, and 8*, a. b. c. The edges of this thinnest joint appear externally only at the angles of the column; internally they enlarge themselves into a kind of intervertebral collar, c. c. c.
A similar alternation in joints of the Pentacrinites sub-angularis is represented in PI, 52, Figs. 4 and 5,