is round and surrounded by numerous long filiform tentacula. The Luanthus Scoticus was found in four fathoms of water in Loch Ryan. 4. Actinia, Linnæus, now restricted to such species as have simple tubular retractile tentacula, and adhere by a broad base. Ehrenberg has separated such Actinia as have a glandular epidermis, under the name of Cribrina. From the glands protrude long filaments, the uses of which are unknown. The tentacula of all the species are (contrary to the supposition of Ehrenberg) perforate at their extremities. [ACTINIA.] The subgenus Adamsia has been constituted, by Professor E. Forbes, for the reception of the curious parasitical Actinia maculata, which envelopes the mouths of dead shells, generally selecting such as have been previously invested by the Alcyonidium echinatum. As such shells are frequently inhabited at the same time by the Hermit Crab, not a few naturalists have mistaken the coincidence for some necessary and mysterious friendship of the zoophyte for the crustacean. 5. Anthea, Johnston, includes such Actiniæ as have not the power of retracting their tentacula. Several of the species grow to a large size. Example, Anthea Tuedice, Johnston, Brit. Zoophytes,' p. 222, fig. 33. 6. Actinoloba, Blainville (Metridium, Oken). Species in which the oral disk is divided at the margin into more or less rounded lobes, which bear short simple tentacula. Example, A. dianthus, Phil. Trans.,' lvii., tab. 19, fig. 8. 7. Capneu, Forbes, of which one species only is known. The disk is round with several circles of exceedingly short tubercular retractile tentacula, and the body is in part invested with a peculiar epidermis, which is divided at the margin into eight lobes. Annals of Natural History,' Example, C. sanguinea. vol. vii., pl. 1, fig. 1. Irish Sea. C. Sea-Anemonies having more or less pinnate tentacula. 8. Actineria, Quoy and Gaimard. Such as have the entire disk covered by very small villose ramified tentacula. Example, A. villosa, Quoy and Gaimard. Voy. Astrolabe, Zooph.,' pl. 49, figs. 1, 2. Tonga Islands. 9. Actinodendron, Quoy and Gaimard. Species having very long arborescent tentacula disposed in one or two series on the oral disk. Example, A. alcyonoideum. Voy. Ast., pl. 48, figs. 1, 2. This animal is more than a foot in height, and secretes a stinging mucus. 10. Thalassianthus, Leuckart. One species only known, the T. aster, an inhabitant of the Red Sea, figured in the plates to Rüppell's 'Voyage.' Its tentacula are numerous, short, and pinnate. It is probably identical with the Epicladia of Ehrenberg. The tentacula are of 11. Heterodactyla, Ehrenberg. two sorts, some simple and others pinnate. Example, H. Hemprichii. Red Sea. 12. Megalictis, Ehrenberg, founded on an animal from the same locality with the last, and characterized by having all the tentacula arborescent, but the internal ones are the larger and more pinnate, and have their extremities hollowed into a sort of socket. Example, Megalictis Hemprichii. Family III. Zoanthide. The genera of this family are few, and the animals included in them have by some been mistaken for Alcyonia. 1. Zoanthus, Cuvier.-The body is elongated, conic. and pedunculated, springing from a base common to several individuals. The mouth is linear and transverse, in the centre of a disk bordered by short slender tentacula. Example, Z. Solanderi. West Indies. 2. Mamillifera, Lesueur (Polythoe, Lamoureux). The body is coriaceous, short, and mammiliform; slightly enlarged at its buccal extremity, and provided with several rows of marginal tentacula. It is subpedunculated at the base, and springs from a common expansion. Example, M. auriculata. West India Islands. 1, Zoanthus Solanderi; 2, Corticifera glareola; 3, Mamillifera auriculats 3. Corticifera, Lesueur. Body short, cylindric, having a longitudinal mouth surrounded by petaliform tentacula at one extremity, and merged at the other into a common mass with numerous similar individuals, so that a solid poliferous crust is formed. Thus there is a transition through this genus from the soft Actinia to the corals. Example, C. glareola. Guadaloupe. The best account of the Zoanthidæ, with excellent figures, will be found in the papers of Lesueur, in the first volume of the Transactions of the Philadelphia Academy.' Family IV. Madreporida. The animals which form the harder and larger corals closely resemble the Actinia. Generally, as far as they have been examined, there is but little variety among them; but judging from the differences presented by one or two types, it is probable that future researches will show a greater diversity of form in this family than is at present admitted. Thus though the usual form of the coral animal is that of a cylinder terminated by a disk surrounded by simple tentacula, in Fungia we have the tentacula irregularly scattered over a broad expansion; and in Desmophyllum they are reduced to the appearance of irregular folds. a universal warm climate during the earlier epochs of the world's history. ZOBEL, BENJAMIN, the inventor of marmotinto, was born in 1762, at Memmingen in Bavaria. He received his education at the government school of that city, and acquired the rudiments of drawing from one of the monks belonging to the convent of Ottobeuern. In 1781 he went to Amsterdam, where he resided for two years, occupying himself chiefly in portrait-painting. In 1783 he came to London, where he formed acquaintance with Morland and Schweickhardt, the latter of whom was employed at Windsor Castle by George III.'s table-decker.' It was then the custom to ornament the royal dinner-table by having a silver plateau extending along the centre, on which were strewed various coloured sands or marble dust, in fanciful designs of fruit, flowers, arabesque-work, &c. For this an artist of considerable talent and of great freedom of hand was required. On the retirement of Schweickhardt, Zobel was appointed; and he continued to fill the office for a considerable period. Ornamenting the royal table in the manner just described was a daily occupation, the sands not being cemented by any substance. From this occupation arose the idea in the mind of Zobel of producing a finished and permanent picture, by the use of some substance by which the sands might be fixed. After various experiments, a composition (in which gum-arabic and spirits of wine formed the chief ingredients) was found to answer the best. The subject of the picture having been designed either on pannel or milled board, a coating of the glutinous substance was spread over it; the different coloured sands were then used in a similar manner as that employed in decking the royal table, viz. by strewing them from a piece of card held at various elevations, according to the strength or softness of the tint required. Thus was formed a picture, not subject to decay, and perfectly permanent in all its parts, and this was called by the inventor, Marmotinto. Some of the best specimens of this peculiar art were formerly in the possession of the late Duke of York, but were sold, at his death, at Oatlands. Several are still among the collections of paintings belonging to the Duke of Northumberland and Sir Willoughby Gordon. Painting on gold and silver grounds in transparent colours for the representation of cabinets of humming-birds &c. was also practised with eminent success by Zobe He died in 1831. ZO'DIAC (in Greek Zodiakóç kúrλos, the Zodia circle') is a name given to a zone of the visible heavens. extending in breadth to certain equal distances on both sides of a great circle of the celestial sphere, in the plane of the earth's orbit produced. This circle, with which the apparent annual path of the sun coincides, is called the ecliptic; at present it makes with the plane of the earth's equator an angle equal to about 23° 27′ 35′′, and it is divided into twelve equal parts, called signs, which receive their denominations froni those of the figures intended to designate the constellations or groups of stars about it. Most of the figures being those of animals, the name of zodiac (from diov, zódion, the diminutive of Lyov, zövn, 'an animal') has, in consequence, been applied to the zone. The planes of the orbits cf all the planets, when produced to the celestial sphere, are supposed to be comprehended within the breadth of the zodiac, and that breadth is determined by two small circles parallel to the plane of the ecliptic. Before the discovery of the planets Ceres, Pallas, Juno, and Vesta, the greatest inclination of the orbit of a planet to the ecliptic scarcely exceeded 7 degrees, and therefore the breadth of the zodiacal zone was imagined to be about 16 degrees, or 8 degrees on each side northward and southward of the ecliptic. The orbit of Pallas (that which deviates most from the ecliptic) is inclined about 35 degrees to that plane; and it might now be understood that the breadth of the zone is about 70 degrees. The line in which the plane of the ecaptic intersects that of the terrestrial equator, being produced indefinitely, cuts the celestial sphere in two points diametrically opposite to each other; and one of these meeting the heavens, in the age of the earliest Greek astronomy, near certain stars forming a constellation to which the figure of a ram (Aries) was assigned, is generally called the first point of Aries. From this point are reckoned, on the ecliptic, the longitudes of celestial bodies; and on the equator, their VOL. XXVII. 5 I right ascensions. The twelve equal parts or signs into which the ecliptic is divided are distinguished by the names of the constellations which, in the age above alluded to, fell within their respective extents in longitude; and the names both of the signs and constellations are as follow:-Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, and Pisces. The distribution of all the visible stars into groups or constellations was the first step in laying the foundation of astronomical science. It must have taken place in the earliest ages of the world; and there is the highest degree of probability that the zodiacs of all nations have been derived from a common source, though in passing from one people to another it may be easily conceived that the figures would suffer changes from the vanity or caprice of individuals. Among the antients, the place of the sun in the zodiac served to regulate the seasons of the year; the representations of the figures associated with the groups of stars were almost constant ornaments of the religious edifices; and superstition assigned to the regions of space influences on the lives and characters of men depending upon the qualities of the animals or objects which distinguished the constellations in the corresponding parts of the celestial sphere. The loss of the writings of the antient Babylonians, and the entire destruction of their edifices, have deprived the world of every monument by which light might be thrown on the state of astronomy among a people whose priests, according to Strabo, were mostly engaged in the study of the science. In fact our information respecting it consists chiefly of the notices given by Ptolemy concerning a few of their observations, and from the evidence of Geminus, Diodorus Siculus states (Biblioth. Histor., ii. 30) that the Babylonians had twelve chief deities, to each of whom they assigned a month, and one of the so-called twelve animals,' by which he means the twelve parts of the zodiac; and from this it may be inferred that they divided the zodiac into twelve signs. Sextus Empiricus (Adversus Math., lib. v.) makes a like statement, and shows how, by means of a clepsydra, the division was or may have been made. With respect to the astronomica' monuments which adorned their edifices, a few fragments only of stone, having on them figures which may or may not have been intended as representations of those which distinguish the constellations, have been dug up near Bagdad; and the most remarkable of these is one having on its face a solar disk accompanied by a serpent: the figure may have designated Ophiuchus, and it is possible that it may have been part of a Chaldæan planisphere. The division of the zodiac into twelve signs may have been originally made for the convenience of distinguishing the portions which the sun passes through in the several months; and a division into twenty-eight parts is alluded to by Geminus (Eloaywyn sis Pairóμeva), which was probably made to denote the space daily described by the moon by her proper motion. The former division was used by the Egyptians, the Greeks, and by all the civilized nations of Asia; and the latter is found among the Persians, Arabs, Hindus, and Chinese: the twentyeight parts are called the stations or abodes of the moon because this luminary is in some one of them each day, apparently of an astronomical character, are found in several other apartments within the same temple; and in the ceiling of its portico are figures resembling constellations, among which are those of the zodiac disposed in two lines, one near each extremity of the portico, and parallel to the longitudinal axis of the temple. Except the zodiacal figures, scarcely any in the ceiling resemble those which are now assigned to the constellations; and a great effort of the imagination is required to discover in what manner they may be considered as emblems of the latter. From the zodiacal figures only has it been possible to form opinions concerning the nature of the projection employed in the execution of the work, and the epoch to which the aspect of the heavens represented by it is to be referred. epoch.M. Biot afterwards calculated for that epoch the places of the principal stars, and determined their situations on a plane by the rules of the projection supposed, as above mentioned, to have been used in constructing the Egyptian monument: on comparing the map so formed with an exact copy of the planisphere, he found the stars The zodiacal figures in the apartment first mentioned to fall upon or near the figures to which they were are disposed nearly within the breadth of an annulus presumed to belong. Thus the stars of Ursa Minor fall formed by two circles, whose common centre is at some near the centre, precisely on the figure of an animal redistance southward from the centre of the whole; the sembling a dog or wolf, probably the cynosura of the Greeks; figure which is conceived to represent Cancer is however and those of Orion on the figure of a man, apparently inwithin the space inclosed by the interior circumference of tended for Horus, the son of Osiris, to whom, according to the annulus, and nearly opposite the interval between Plutarch (De Iside et Osiride), Orion was consecrated. Gemini and Leo; that interval being occupied by a human Several indications exist in the planisphere of an intenfigure with a bird's head, above which is a bird and certain tional displacement of the figures designating the constelhieroglyphical symbols. The figure of Cancer is also sur-lations. In some cases, apparently when a constellation mounted by a hieroglyphical symbol, which, according to could not be conveniently introduced in its proper place Visconti, seems to express a proper name. for want of room, it has been transferred to the margin in the direction of a line drawn from the centre through the true place of the constellation. In other cases a constellation appears to be removed and a hieroglyphic figure substituted for it. Thus a line drawn from the centre of the planisphere, through Taurus, leads, near the margin, to a group of seven stars, which probably designate the Pleiades; and near it is another group, which may represent the Hyades. Again, between Aries and Pisces, and a little above them, is an animal in a sitting posture, which The first discoverers of this antient monument imme- is found to coincide with the computed places of the stars diately perceived that the horary or declination circles, if in Cassiopeia; and near the margin of the planisphere, in drawn upon it, would be represented by straight lines di- a line drawn through the centre and this animal, there is verging from the centre, the latter is consequently the pole a human figure seated in a chair, as Cassiopeia is always of the equator; but we are indebted to M. Biot (Recherches represented. In a few cases some emblem of a constellasur l'Astronomie Egyptienne) for the very probable ideation is found at the margin opposite the figure denoting that the space within the exterior circle represents a deve- the constellation: thus the head of a ram surmounted by a lopment of the whole surface of the celestial sphere, the winged globe is in the direction of a line drawn from radii of the circle being equal to half the circumferences of the centre through the front of Aries in the zodiacal the hour-circles, so that the exterior circle represents the ring. A great figure, which is supposed to represent a south pole of the equator in the heavens. The figures of hippopotamus, is situated near the centre of the planithe constellations are supposed to be placed on the radii sphere in a place corresponding to a part of the heavens corresponding to the circumferences of the hour-circles very near Ursa Major, but where there are no remarkable passing through the groups of stars to which the figures stars; and M. Biot conjectures that the animal may be an belong, and at distances from the centre of the planisphere emblem of that constellation: he conceives that it may equal to the angular distances of the figures from the indicate Typhon, who, according to Plutarch (De Iside), is north pole of the equator. The distortion produced by represented by a hippopotamus, and to whom Ursa Major such a development of a spherical surface is evidently very is assigned. That the antient Egyptians had a constelgreat near the margin; but a spectator when duly in- lation which was designated by this name is stated by structed, on comparing the figures near the centre with Plutarch and by Diodorus Siculus (i. 27); the latter has the groups of stars about the north pole in the heavens, given translations of two inscriptions in hieroglyphics, might distinguish those to which the figures were intended which appear to have existed in his time; and in one of to refer; and the apartment without a roof, adjoining that these Osiris is made to say that he had been to the uninwhich contained the planisphere, is supposed to have been habited parts of India, to the regions of the Bear, and intended for the purpose of facilitating such comparison. to the sources of the Ister (Danube). One property of the species of projection or development just mentioned is, that in the direction of a line passing through the centre, or pole, the distance between two points corresponding to two which are diametrically opposite to one another in the heavens is equal to half the circumference of a great circle of the sphere; and M. Biot found that this condition is satisfied by the planisphere as nearly as can be expected in a representation which does not admit of great precision. In order to ascertain, if possible, the epoch of the planisphere, M. Biot assumed as correct the positions of four stars upon it, which, being accompanied by figures of men and by hieroglyphical symbols, appeared to have been distinguished on account of some particular interest attached to them; and concluding from their positions with respect to the nearest zodiacal signs that they must represent Fomalhaut, Antares, Arcturus, and ẞ Pegasi, he first verified them by the near agreement of their measured distances from each other on the planisphere with the distances obtained by computation from their known angular distances in the heavens; then computing the angles of the triangle formed by two of the stars and the centre, or pole, of the planisphere, and also the angles of the triangle in the heavens between the arcs joining the two stars and the pole of the ecliptic in 1750, he found, by comparison, the latititude and longitude of the centre of the planisphere with respect to the positions of the ecliptic and the equinoctial point for hat year. The position of the centre, thus found, is that wich the pole of the world must have occupied about the year 716 B.C.; and he thence concludes that the planisphere presents the state of the heavens at the latter | In the direction of a line drawn from the centre of the planisphere, towards the north, and passing through the figure of Cancer, is the representation of a cow having a great star between its horns; and near it, in the direction of a line coinciding with the longitudinal axis of the temple is a tall lotus-stem surmounted by a hawk, the symbol of deity. On this stem the place of Sirius, computed for the epoch of the planisphere, is found to fall; and the cow probably represents Isis, to whom the star Sirius was consecrated. The solsticial colure being due north and south, it is probable that the planisphere was intended to show the aspect of the heavens at the time of the vernal equinox, when the colures pass through the four cardinal points of the horizon; and the line passing through Cancer and the cow being in the plane of the solsticial colure is an indication that at midsummer, at the epoch of the planisphere, Sirius rose with the stars of Cancer. The line representing the direction of the equinoctial colure passes, on the eastern side, between two symbolical figures of men, a little way from which is a small figure (supposed to be Harpocrates) issuing from a lotus-flower, and having above his head a star with a hieroglyphical inscription. According to Plutarch (De Iside) the Egyptians represented the rising sun by a child issuing from a lotus; and hence it is inferred that the symbols indicate the rising of the sun in the east point of the horizon on the day of the vernal equinox. The heads of all the figures, with scarcely an exception, tend towards the centre of the planisphere, and the figures in the southern half of the zodiac are arranged so that, to a spectator standing in the centre of the room with his face to the south, and looking upwards, they must have appeared as if moving from east to west; that is in the direction of the apparent diurnal motion of the heavens. The longer axis of the temple is inclined to the meridian in an angle of about 17 degrees, and the walls are directed so that the points at which the remarkable stars Sirius and Antares must have seemed to rise coincided with the directions of the north and south ends of the building. A temple near Esne (Latopolis), in the portico of which is a representation of the zodiacal signs, is disposed so that the longitudinal walls tend to the points at which Antares and Sirius set; and though no great stress ought to be laid upon this circumstance, there is some probability that the dispositions may have been intentional, since no reason can be assigned why, otherwise, the temples should not, like the pyramids, have had their walls directed to the cardinal points of the horizon. The golden circle of Osymandyas, which is mentioned by Diodorus Siculus (i. 49) as being placed in the tomb of that antient king at Thebes, was 365 cubits in circumference, and to each cubit was assigned one of the 365 days of the year, with the risings and settings of the stars for each day marked on the several Vivisions. The ceiling of the portico belonging to the temple at Denderah is nearly covered with sculptured figures, many of which resemble those in the circular planisphere, and the twelve signs of the zodiac are distinctly represented in two bands parallel to the axis of the building: six of the figures appear to be entering the temple on the eastern side of the portico, and of these Cancer is the last; the other six, of which the first is Leo, appear to be quitting it on the western side, so that (the front of the portico being towards the north) the direction of their motion corresponds to that of the apparent diurnal rotation. Within the two lines of figures are those which belong to the northern constellations, and beyond them, near the eastern and western extremities of the portico, are figures relating to the southern constellations. Among the former is a numan figure surrounded by seven stars, disposed similarly to those of Ursa Major in the heavens, and near them is a lotus-stem surmounted by a hawk, like that which in the circular planisphere is in the place of Sirius this emblem in the planisphere of the portico is therefore supposed to be an indication of Sirius; and the opinion is confirmed by the fact that it is preceded by a cow (Isis) and a great hieroglyphical inscription. In the planisphere of the portico, as well as in that of the temple, the figure supposed to be that of Cancer is placed on one side of the position which it should occupy among the zodiacal constellations; and this circumstance has given rise to a doubt concerning the justness of that supposition. Some persons have imagined that the figure might have been intended for the mythological scarabeus; but as in this temple, as well as in those at Esne, it has eight feet, while the scarabeus has but six, it is more probable that it represents the zodiacal sign; and that, agreeably to the hypothesis of Biot, the displacement was in order to make room for some emblem. In fact, the place of Cancer is, in the portico, occupied by a head of Isis, which is plunged in the solar rays; and, since Sirius was consecrated to Isis, it is reasonable to suppose that the emblem was intended to express that, at the epoch of the planispheres, the star Sirius rose heliacally. By calculation it is ascertained that about 700 years before Christ, in the latitude of Denderah, Sirius rose with the stars of Cancer when the sun was in that constellation, that is, at the summer solstice. The two temples at Esne have, in the ceilings of their porticoes, representations of the twelve zodiacal constellations in two lines parallel to the axes of the buildings. In the smaller temple six of the figures appear to be entering on the southern side, and six to be issuing on the northern side: the front of the portico being towards the east, the direction of their movement corresponds, consequently, to that of the diurnal rotation, as in the temple at Denderah; but there is this difference in the division of the figures, that, at Esne, Leo is the last to enter, and Virgo the first to quit the temple. M. Biot endeavours to account for this difference by the different inclinations which the axes of the two temples have to the meridian; the axis of the temple at Denderah deviating 17 degrees, and that of the small temple at Esne 71 degrees, both of them being from the north towards the east. He observes that, in the former temple, a meridian line passing through the centre of the circular planisphere cuts the zodiacal band in Cancer towards the north, and in Capricorn towards the south; thus dividing the twelve figures so that the six which are on the western side constitute all those which at a certain hour are descending towards the west, and those which are on the eastern side are ascending towards the meridian. At the head of this descending series is Leo, which is the first to pass the inferior meridian and enter the eastern series; and at the head of the ascending series is Aquarius, which is passing the upper meridian: this distribution corresponds to that which is represented in the zodiac of the portico. A like correspondence would be found to exist in both the temples at Esne if a circular planisphere were supposed to be placed in the ceiling of each, with the lotus-stem in the longitudinal axis, towards the north, and the planisphere were cut by a meridian-line so as to divide the figures into such as ascend and such as descend. That there were among the antient Egyptians a variety of sculptured representations of the heavens is evident, since the planisphere described by Scaliger, in his Notes on Manilius,' contained, among many animals having no correspondence in form or situation with those which have been mentioned, the figure of a man holding a scythe, and of another who is killing a bear; and in the Mémoires de l'Académie des Sciences,' 1708, there is described, by M. Bianchini, a fragment of an Egyptian planisphere consisting of a circular space surrounded by five concentric bands: in the centre are two bears separated by a serpent, as in the present spheres; and in the nearest band are twelve figures representing constellations, most of which differ from the zodiacal signs above described; the place of Gemini, for example, being occupied by a serpent. In the two next bands are the signs of the Greek zodiac, and on the exterior of these is a band divided into 36 parts, in each of which is a deity: these are the spaces of 10 degrees, into which, in the East, the zodiac was sometimes divided. There can be little doubt that the Egyptians and Chaldæans distinguished the groups of stars in the visible heavens by the figures or symbols of the deities which they worshipped, and of the men who, among them, had signalized themselves by great actions; but it has been also assumed, that the names of the zodiacal constellations were given from circumstances relating to the apparent motion of the sun, to the labours of husbandry, or to the produc tions of nature in different seasons. Macrobius mentions (Saturnal., lib. i.) that the constellation in which the s is, at the season when he ascends from the winter solstice towards the equator, received the name of Capricornus, because the goat is an animal accustomed to ascend to the highest points of ground; and that the constellation in which the sun is when he returns from the summer solstice towards the south was designated Cancer from the crab being an animal which is said to have a backward movement. Bishop Warburton in this country, and M. Pluché in France, carrying out the same idea, have imagined that the constellations Aries, Taurus and Gemini received their names from the young of animals being brought to the fields in the spring; that Leo indicates the violent heats of summer, and Virgo, presumed to be a gleaner, denotes the time of harvest, and so on. M. Dupuis, assuming that the zodiacal constellations were first imagined in Egypt, and that they indicated circumstances connected with the labours of husbandry in the different months of the year, endeavoured to ascertain at what epoch, in the climate of Egypt, the symbols would be in accordance with the circumstances which they were supposed to represent; and the result of his inquiry was, that the agreement cou have subsisted only when the vernal equinox was in the constellation Libra. At present it is in the constellation Pisces; and computing the time during which, by the effect of precession, the equinoctial points would move over about half the circumference of the ecliptic, he assigned 15,000 years before the Christian æra for the time of the invention of the zodiac. This extravagant epoch he afterwards reduced to about 4000 years before Christ. (Origine des Cultes, 1796.) M. Fourier, in his 'Recherches sur les Sciences et le Gouvernement de l'Egypte,' assumes that the representation of the head of Isis partly plunged in the solar rays near the figure of Cancer, among the sculptures in the portico of the temple at Denderah, is an emblem of the heliacal rising of Sirius when the sun was in the sign, or in |