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examples from Sussex and Kent. The chalk-flints often have remains of Goniasters attached to the surface; in the neighbourhood of Northfleet, specimens of this kind of great beauty have been collected.'

CRINOIDEA.-Encrinites and Pentacrinites.-Wall-Case G. -The Crinoideæ have a fixed pedicle or process of attachment, an articulated stem composed of numerous separate pieces of a solid calcareous substance, and a receptacle formed of a series of plates, to the upper margin of which are attached arms or tentacula. They consist of two groups; one with smooth, subcylindrical stems-the Encrinites; the other in which the stems are pentangular-Pentacrinites.

The fossil remains of the Crinoidea have received the name of Stone-lilies, from the resemblance of the receptacle of some species when the animal is in a state of repose to a closed lily or tulip. Only one living species is known, namely, the Pentacrinus Caput-Medusa, an inhabitant of the Caribbean Sea, of which there is a specimen at the bottom of this Case. This animal has a long jointed stem, which is fixed at its base by a pedicle or root-like processes, and supports a vase or receptacle, formed of a series of calcareous plates closely adjusted to each other, in which the viscera are contained. The upper part of the receptacle is covered by a plated integument, in which there is an opening for the mouth. From the brim or margin, proceed ten multiradiate arms, which subdivide into branches of extreme tenuity; the upper and inner side of the arms support numerous articulated cirri, or feelers. The ossicula composing the column of support are pentangular, very numerous, and articulated by striated pentapetalous surfaces, and have a central perforation; and there are articulated side-arms, or tentacula, that radiate from the column in groups of five, at different points. In a living state the skeleton is covered by the integuments which secrete it; the mouth is situated in the centre of the plated integument of the receptacle, and surrounded by the arms, which, when spread out, with their numerous cirri, form a net for the capture of the prey, and are the organs by which it is conveyed

to the mouth.

The fossil remains consist of the ossicula, or bones of the

1 "Pictorial Atlas," Pl. LIII. figs. 1 and 3.

column, arms, and tentacula; of the plates of the receptacle ; and of the peduncle, or process of attachment by which the animal was permanently fixed to the rock. The peduncle is in some species flat and expanded, like that of the Gorgonia; in others, it consists of long jointed processes. These several parts are commonly found detached, and intermingled with detritus in the strata; throughout extensive beds of encrinital marble, vestiges of the receptacle are but seldom discoverable. In some localities the skeletons are preserved entire, and spread out on the surface of the layers of shale, clay, or limestone, as if the animals had been enveloped by the soft deposit when alive in their native seas, as is the case in many of the beautiful specimens before us.

These remarks will convey a general idea of the nature of the beings whose remains are scattered through certain rocks in such inconceivable quantities; for, much as the columns may differ in form, the ossicula in their markings, and the plates of the receptacle in their configuration and ornament, the same type of structure prevails throughout the family.

These durable parts of the animal fabric occur in immense quantities in the ancient secondary deposits; and in many parts of England, and of northern Europe and America, entire mountain-chains are chiefly composed of the bones and detritus of Crinoidea, belonging to numerous extinct species and genera.

Screw or Pulley-stones.-Upper Shelf F.-The circular, or pentagonal channel formed by the united ossicula of the column, has given rise to the curious fossils called, in Derbyshire, Screw, or Pulley-stones, which are flint casts of these cavities. These bodies occur in the chert, which is interstratified with the mountain limestone; the siliceous matter, when fluid, having filled up the channels, and invested the calcareous stems: the latter have since been dissolved, and consequently solid cylinders of flint, resembling a pulley, alone remain; the masses of chert are often impressed with the ornamented articulating surfaces of the ossicula, or trochites. These fossils are sometimes mineralized by galena, or sulphuret of lead, as in the specimens in this cabinet.

In the quarries on Middeton Moor, near Cromford, Derbyshire, where extensive beds of limestone composed of crinoideal remains are worked for chimney-pieces, and other ornamental

purposes, beautiful examples of these fossils may be obtained.

The cavities of the columns and ossicula are often filled with white calcareous spar; while the ground of the marble is of a dark reddish brown colour. In other varieties of the Derbyshire entrochal limestones, the substance of the fossils is white, and the ground dark grey or brown; both kinds, when worked into ornaments, are very beautiful and interesting.'

MARSUPITES (M. Milleri).—Wall-Case G. On the upper and right-hand Shelf.-The chalk fossils labelled Marsupites in the upper compartment of this cabinet belong to an interesting extinct type of Stelleridæ, that forms a connecting link between the Starfishes and the Crinoideans. Like the former, it is free, and destitute of a column of support or pedicle; while it has the receptacle composed of articulated plates, and flexible arms, as in the lily-shaped animals. These fossils are peculiar to the white chalk deposits, and were first described by Mr. Parkinson in the "Organic Remains of a Former World," under the name of "Tortoise Encrinite,” that excellent observer having supposed, from the sculpturing of the plates of certain specimens, that they were related to the Actinocrinites, and had a jointed column. The true characters of the original were first pointed out in my "Fossils of the South Downs;" and the name Marsupites, suggested by the purse-like form of the closed specimens, was adopted.

2

The receptacle of the Marsupite is of a subovate shape, rounded and entire at the dorsal aspect, consisting of a large central plate, and a series of polygonal plates, with five arms attached to the margin. The opening of the receptacle was covered by an integument supported by numerous small semilunar ossicula, in the centre or side of which the buccal aperture, or mouth, was placed. The external surface of the receptacle is smooth in some examples; in others it is deeply sculptured with granulated lines and furrows, disposed in a radiated manner; and in a few instances the sculpturing is rugous and irregular. The Marsupites vary in size from one to three inches in length. The receptacle is very capacious

1 "Pictorial Atlas," Pl. XLIX. for figures of pulley-stones and encrinital marbles and Pl. XLVII. for representations of a great variety of stems of Encrinites and Pentacrinites.

2 "The Fossils of the South Downs," or "Illustration of the Geology of Sussex," p. 184, pl. xvi.

compared with that of the Crinoideæ. The central' plate is large and of a pentagonal form, without the slightest trace of a process of attachment: five pentagonal pieces are united to the sides of the central plate, and above these a like number of hexagonals, which receive the five upper plates that form the margin; each of the latter has a semilunar depression to articulate with the first joint of the arm.

Detached plates and ossicula of marsupites are not uncommon in the chalk of Kent and Sussex; nearly entire receptacles, filled with chalk or flint, are occasionally found in the pits near Lewes and Brighton; but examples with remains of the arms are extremely rare; and I have seen but one specimen (the one in the Case before us, which I collected from the Sussex chalk), in which the plates of the integument that covered the opening of the receptacle are preserved.1

APIOCRINITES. (A. Parkinsoni.)-Pear-Encrinite of Bradford.-Wall-case G.-The "Pear-Encrinite," from its size, and the abundance of its remains in one particular locality, is the most generally known of all the British fossil Crinoideæ. It abounds in the beds of oolite, especially in the quarries on the heights above the picturesquely situated town of Bradford, in Wiltshire. The receptacle, detached ossicula, and the pedicles or roots, are very common; and in some instances the entire skeleton from the peduncle to the extremities of the arms, is met with. The late Channing Pearce, Esq., of Bradford, by unremitting attention to the collecting of these fossils, obtained the beautiful specimens deposited in this Case.

This Apiocrinite has a smooth receptacle of a pyriform shape, composed of large plates with radiated articulating surfaces; the stem is short and strong; the arms simple, resembling those of the marsupite; the peduncle spreads out into an expanded base, which is firmly attached to the rock, like that of the Gorgonia, and is generally of a rich purple colour. Sir Charles Lyell mentions an interesting fact relating to the occurrence of these fossils in the oolite strata at Bradford. In Bur

1 See "Medals of Creation," p. 319, Lign. 70; “Pictorial Atlas,"

Pl. XLVI., fig. 24; "Wonders of Geology," p. 652.

2 See "Wonders of Geology," p. 653; "Pict. Atlas," Pl. L.

field quarry, on the heights that overlook the town, a bed of limestone was exposed, the upper surface of which was incrusted with the stony peduncles or roots of Apiocrinites; upon this stratum was a layer of clay, in which were innumerable remains of receptacles and ossicula of stems and arms; some of the stems were erect, others prostrate, and throughout the clay were the dismembered remains. This submarine forest of Crinoideans must therefore have flourished in the clear sea-water, till invaded by a current loaded with mud that overwhelmed the living zoophytes, and entombed them in the argillaceous deposit in which their fossil remains are embedded.

LILY ENCRINITE. (Encrinus liliiformis.) Wall-case G. Left upper Shelf. This exquisite species of Crinoidea is equally interesting and attractive to the amateur collector and the naturalist. Its remains do not occur in the British strata, and are only known in the muschelkalk of Lower Saxony. The specimens in this country are chiefly from Erkerode, in Brunswick; they are found in a layer about eighteen inches thick, of a soft argillaceous cream-coloured limestone, which is chiefly made up of trochites, (i.e. detached ossicula of the stem), and a few fragile shells and corals.

The receptacle of the Lily Encrinite is smooth, and in the form of a depressed vase; its base is composed of five plates, upon which are placed three successive series of other plates, with the uppermost of which the arms articulate. The stem is formed of numerous perforated round ossicles, articulated to each other by radiated grooved surfaces, and becoming somewhat pentangular, and alternately larger and smaller towards the summit, to which the receptacle is fixed; a construction admitting of great freedom of motion.

This Encrinite when lying in relief on the rock, with its receptacle entirely or partially closed, so strikingly resembles a bud or expanding flower of a lily or tulip, as to justify the popular name of Stone Lily. An exquisite specimen is figured by Mr. Parkinson.' There are a few beautiful examples in the Case before us.

PENTACRINITES.- Wall-case G.—In this group of Crinoideans the ossicles of the columns are angular, generally pentagonal,

1 See "Pictorial Atlas," Pl. XLVIII.; "Wonders of Geology," p. 651.

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