The Milleporx do not appear to be nearly so frequently found in a mineral as in a recent state. Several fossils have been placed among the Millepores, which undoubtedly should rank with the Ma; drepores : such are the Millepora sin plex turbinata, and the Millepora simplex discoides, of Waller and Gesner ; a care fill examination shewing, that these dif fer from the porpital and turbinated Madrepores only in their being formed of numerous tubes, possessing an internal stellated structure.
Of the genus Isis one species only ap pears to be knoWn as a fossil. This spe cies was at first described by Scilla, who at first conjectured it to be the leg-bone of some animal. Specimens are fre quently found in the Calabrian mountains, and have lately been also found in some parts of Wiltshire. Of the genus Celle pora, Antipathes, and Gorgonio., fossil specimens appear to be rather uncom mon.
The Corallo Fungitm of Waller are evi dently the fossil remains of Alcyonia. These have been long described by Yolk mann, Seheuclizer, and others, as fossil fruits, and have obtained, from their re semblance to figs, &e. the appellations of fieoides, caricoides, &c.; whilst others of a different form have been named ly coperditm, fungitx pilcati, &c. A fbssil has even been described by Vollemann and Scheuchzer as a fossil nutmeg. A fossil A lcyonium of a conical form is represented, Plate I. fig. 6.
The Encrini and Pentacrini have been always, and very properly, considered as the most curious of the fossil Zoophytes. The Encrinus (Plate I. fig. 3) possesses the distinguishing character of having its spine, or, as it has been generally called, its tail, composed of cylindrical or orbi cular vertebrx, pierced through their centre, and marked with diverging stria on their articulating surfaces. On the superior termination of these is placed the base of the body of the animal, form ed of five trapezoidal bodies, termed by Rosinus articuli trapezoides, which in close five small bodies, which form the centre of the base ; the whole of these forming that which Rosinus denominated the pentagonal base. From each of these proceed six other bodies, on the two last of each series of which are placed the arms of the animal, which divide into fin gers; from the internal surface of these proceed almost innumerable articulated tentacula. This fossil has long possessed the name of the Encrinus, or stone lily ; its resemblance to that flower having led to the suspicion that it was a petrifaction of a flower, approximating in its form to the lily : its animal origin is however now completely ascertained. Indeed, if a doubt had remained, it would have been removed by the circumstance of the ani mal membrane, or cartilage, having been actually discovered in the fossil, (" Or ganic Remains of a former World," vol. u. p. 166.) Several other species of this Animal are also described in the work just referred to ; but hitherto no recent ani mal has been found which can be referred to this genus.
The fossil Pentacrinus differs from the rncrinus, in its vertebra being of a pen tagonal form, and in its arms, fingers, and tentacula being capable of being much more widely spread and extended than are those of the Encrinus. It appears from Mr. Parkinson's account, that there are several species of this fossil, the ex istence of some recent species of which have been also ascertained.
The encrinital vertebrx (Plate I. fig. 7 a) have been hitherto termed trochit2e when separate, and entrochi when con nected in a series, (Plate L fig. 7.) The single vertebrx of the Pentacrinus have been distinguished as asterize, (Plate I. fig. 8 ; and when united together they have been termed columnar asterix, (Plate I. fig. 8.) Of the Asterix, or Stake Marini, some very few specimens have been found fos sil ; but they occur very rarely, and have, in general, been found in a condition too imperfect to allow of any positive opinion being formed, respecting the species to which they belong.
The fossil Echini are very numerous, upwards of forty species, known only as fossils, being enumerated by the illus trious Linnnus ; to delineate, therefore, even those most deserving of notice could not be here well accomplished ; a cir cumstance, however, which is not so much to be regretted, since, though ma terially different, they approach very nearly in their general form to the recent species. Those which possess a hemi spherical, or a nearly orbicular form, with large mamilla-hike protuberances, and the anus disposed vertically, have been distinguished as the turban echini (echini cidares); those which resemble a shield or buckler in their figure, are termed the shield echini (clypeii ; and one of the largest of these has been nam ed the polar stone by Dr. Plot (Plot's Ox fordshire, p. 91.) When of a depressed circular form, with the anus in the edge of the inferior part, they are the fibula of Klein ; of a conical form, the eagle stone of the Germans (mail, 10einii); with a circular base, the quoit echinus (discoidei, Iaeinii). When the base is an acute oval, the mouth and anus being at the opposite ends, they are termed the helmet echinis, (cassides et galex,A7einii); and when heart-shaped, with a sulcated superior surface, they are called snake's hearts (spatangi, The attempt to particularize the va rious species of fossil shells which have been found would require a large volume: all that can be here done is to notice some of those which totally differ from any which exist in a recent state, and to offer some few remarks on those which approximate, or are perhaps similar to some of the species which are known in a recent state.