PiiyrozoA.] 



MUSEUM OF ANIMATED NATURE. 



411 



lied (o them are the Zoanthi, united by common base 

 to each other, this base being adherent to the rock. 

 Here we have made a great advance in the scale of 

 organization ; we have in the structure of the Ac- 

 tiniae, muscles, a true stomach, and nervous ti)a- 

 ments. 



So far we have endeavoured to render clear an 

 idea of the nature of polypes, simple and compound, 

 cortical or tubular ; we have selected only a few of 

 their principal modifications, by way of illustrating 

 the general nature of the Phytozoa ; our object be- 

 ing in this short introduction to lead the readorfrora 

 the simple unclad polype to the compound forms, 

 where congregated polypes are united into one living 

 whole, while at the same time each acts for itself; 

 one contracting, another expanding, at the same 

 instant. In one sense we may consider each polype 

 as a distinct being ; in another sense, as forming a 

 part of a compound unity through which vitality is 

 equally diffused. In these aggregated forms, the 

 polypes all labour to one end ; they constitute a 

 communitv, every individual of which contributes 

 to the nutrition of the general body. But as there 

 are no nerves, they can neither participate in each 

 other's movements or each other's feelmgs. If one 

 polype be destroyed, the rest are unalfected. We 

 commenced our observations on the Acrita by saying 

 that all ideas of lite derived from a consideration of 

 the higher animals of creation must be banished, 

 and a contemplation of the sponges and Phytozoa 

 will surely justify our remark. Deadness to pain, 

 yet feeling lor light, contractility, expansibility, and 

 motion without muscles; digestion and nutrition 

 without lacteals, absorbents, or blood-vessels; repro- 

 duction by simple division or budlike sprouts ; the 

 vital unity of myriads, and yet their personal dis- 

 tinctness—these are characteristics which surprise 

 the more, the more we reflect upon them ; and when 

 to these characteristics we add those taken from 

 their rude skeletons, their horny tubes, the;r cells, 

 their plant-like forms, and mode of attachment, we 

 must confess that the Phytozoa aie among the most 

 mysterious of living things which the Fiat of Crea- 

 tive Wisdom has called into existence. 



Let us now attend to our pictorial specimens of 

 this class, taking first the Lithophytes, or Stony Phy- 

 tozoa, into consideration. 



To the Family Madrephyllioea of De Blainville 

 belongs the genus Fungia, of which we have already 

 spoken. (See Fig. 3813.) In seme species there 

 appear to be no tentacles, but in others tentacles 

 exist, covering the upper sui face. In Fungia cra.ssi- 

 tentaculata tliese are thick, conical, and hollow, of 

 a brown colour, and transversely striated, terminat- 

 ing in a greenish yellow facet perlbrated by a 

 minute orifice. They are strongly prehensile, urg- 

 ing to the mouth small Crustacea or other animals 

 on which the Fungia subsist. When alarmed the 

 tentacles are withdrawn between the laminae of the 

 calcareous axis, and the flesh shrinks down and 

 accumulates in the interstices. The Fungiae, as we 

 have said, are free, reposing on the sand ; but the 

 Lithophytes, as a rule, are rooted or fixed to the rock 

 which supports their branched expansions or ex- 

 tended masses. To this group belongs the elegant 

 Caryophyllia cyathus. Fig. 3814, in which the gob- 

 let-like cells are elevated upon a fixed calcareous 

 base ; the cups or cells are striated externally, and 

 the polypes which they lodge have a single or double 

 coronet of short, thick, perforated tentacula. The 

 species are numerous. 'I'o the present group belong 

 many forms found only in a fossil state, as Columnaiia, 

 Sfylina, Catenopora, Syringopora, &c. Fig. 381.J re- 

 presents C'atenopora escharoides, from the transition 

 rocks. It is a lamelliferous coral, with tubular and 

 often oval cells, furnished with radiating plates, 

 united laterally into a calcareous polypary of a 

 conical figure, fixed, and composed of verticalfixed 

 lamellae. 



Fig. 3816 represents Syringopora geniculata. 

 Large masses of this coral occur in the carbonifer- 

 ous limestone, composed of tubular vertical cells, 

 radiating interiorly, as may be seen by polishing a 

 portion of the surface transversely to the direction 

 of the tubes.. The Syringoporae were ranked by the 

 older writers as Tubiporae. 



There is a group of corals termed Meandrina, 

 or popularly Brain-corals, of which some splendid 

 specimens may be seen in the British Museum. 

 They are generally in the form of large rounded 

 masses, exhibiting a surface covered with sinuous 

 ridges winding in every direction, and anastomos- 

 ing with each other, like mimic Alps with valleys 

 between ; from the centre of these valleys to the 

 top of the winding ridges are multitudinous linear 

 depressions or pits divided by transverse lamellae. 

 In a state of nature the whole of this mass is co- 

 vered by a gelatinous film, and myriads of polypes, 

 of minute size, with short tentacles, occupy the 

 linear pits ; so that when all become expanded and 

 in action, the surface seems alive with countless 

 beings ; ail ai'tive in the actjuisition of food, or the 

 extension of their calcareous polypary. 

 Vol. II. 



Fig. 3817 represents Meandrina Daedalaea, from 

 the Indian Seas; a, the entire figure, reduced; b, 

 a portion, of the natural size. 



The genus Pavonia comprehends several very 

 elegant lithophytes from the Seas of the East and 

 West Indies and those of the South Saa Islands. 

 They are distinguished by the foliated expansions of 

 the calcareous axis, resembling clusters of cup-like 

 flowers, or those singular fungi which we find 

 growing on the bark of decayed trees. The polypes 

 are destitute of distinct tentacles ; and the cells in 

 which they lodge are confluent, conical, and small. 

 Large masses of these Lithophytes are in the British 

 Museum. 



Fig. 3818 represents Pavonia boletiformis. 



M. de Blainville places under a section which he 

 terms Madrastrasa, various genera, as Astraea, 

 Oculina, &c. 



In Astraea the calcareous mass adheres to rocks, 

 and has the upper surface covered with roundish 

 or subangular depressions or shallow cells, with 

 radiating lamellae. In some species these cells 

 are contiguous, in others they are separated by in- 

 tervals. Many species are known only in a fossil 

 state. It is in the cells of Astraea that the polypes 

 reside ; the mouth is rounded, and placed in a disc 

 furnished sparingly with rather short tentacles, 

 forming a single row. 



Fig. 3819 represents the Astraea ananas. In this 

 the cells are roundish and approximate, with distinct 

 radiating lame loe. 



Fig. ;^820, the Astraea rotulosa, found in the 

 West Indian Seas. The star-like cells are distinct. 



Fig. 3821, AstrEca favosa, common in the East 

 Indian Seas. The stariy cells are contiguous. 



The polypes are all united by a gelatinous ex- 

 pansion covering the calcareous coral. Many are 

 very beautifully coloured, resembling green flowers 

 with a deep blue disc. 



In the genus Oculina the coral is fixed and 

 branching, each branch being studded with ele- 

 vated cells having internal calcareous radiations ; 

 the whole forming an elegant arborescent mass. 

 The polypes do not appear to be known. 



Fig. 3822 represents the Oculina axillaris. M. 

 de Blainville distinguishes a tribe of Lithophytes or 

 stony Zoanlharia under the title of Madreporaea : 

 the corals of this section are mostly aborescent, 

 with the cells partially lamellated, the interstices 

 being constantly porous. To these Madrepores be- 

 longs the genus Dentipora: this coral is arbores- 

 cent, with deep, circular, elevated cells, each having 

 ten internal dentiform lamellae. The polypes are 

 unknown. 



Fig. 3823 represents Dentipora virginea: o, a 



fjortion, magnified ; 6, a section of one of the lamel- 

 ated cells, magnified. 



Another remarkable genus is Gemmipora. In 

 this form the calcareous axis is arboiescent or 

 laminilbrm, fixed, and of a porous structure ; the 

 cells are deep, cylindrical, and somewhat lamel- 

 lated within; their edges are elevated. The animals 

 are destitute of tentacles. Fig. 3824 represents 

 Gemmipora mesenterina, diminished : a, a portion, 

 of the natural size. 



In the genus Madrepora the calcareous axis is 

 arborescent and very porous ; the branches and 

 expansions are crowded with small elevated cells, 

 giving them a roughened appearance. The minute 

 multitudinous polypes have twelve simple tentacles. 

 There are several fossil as well as recent species 

 described. 



Fig. 382.5 represents Madrepora abrotanoides, di- 

 minished : a, the termination of one of the branches, 

 of the natural size. 



The genus Palmipora presents us with branched 

 forms of coral, but the branches end palmate or digi- 

 tated ; and the cells are small, scattered, and not ele- 

 vated. The branched mass is fixed, and of a porous 

 structure, being externally reticulated : animals un- 

 known. Fig. 3820 represents Palmipora alcicornis 

 (Miliepora alcicornis, Linn.). 



In the genus Heliopoia the fixed calcareous poly- 

 pary is of an irregular form and of porous structure; 

 the cells are cylindrical, not elevated, and par- 

 tially lamellated internally. The polypes are short, 

 with a coronet of fifteen or sixteen tentacles. 



Fig. 3827 represents Heliopoia ccerulea (Pocil- 

 lopora caerulea, Lamarck), from the equatorial .seas. 



In Alveopora the cells are deep, polygonal, ir- 

 regular, with perforated or reticulated walls; the 

 mass is of porous structure. The polypes have 

 twelve simple tentacula. Fig. 3828 represents Al- 

 veopora retepora. 



In the genus Porifes the polypary is fixed and 

 rudely branched or diversilbrm, and of porous tex- 

 ture. The cells are polygonal, unequal, and incom- 

 pletely radiated. The polypes have twelve short 

 tentacles. 



Fig. 3829 represents Porites clavaria, with club- 

 shaped branches. 



Fig. 3830 represents the polypes of Cladoeora ces- 

 pitosa, showing the mouth and the disc, surrounded 



by short tentacles. The lower figure is of the natu- 

 ral size. 



We may now passto a family termed Millcporidae, 

 which is thus described by NI. de Blainville : — The 

 polypes are in general very slender, and provided 

 with a single circle of slender tentacles ; the cells 

 are often of considerable size, but always without 

 lamellae or striae, within or without the tubes. The 

 polypary is fixed, and varies in shape. Remov- 

 ing from this family the palmated kinds to form 

 the genus Palmipora among the Madrephyllioea, M. 

 de Blainville still enumerates twenty-three genera, 

 arranged in groups according to the characters of 

 the cells. Numerous species exist only in a fossil 

 state, in the transition and carboniferous strata. 



In Favosites the cells are polygonal, prismatic, 

 contiguous, vertical, or diverging; the walls of each 

 cell are pierced with, and the inside is divided by, 

 transverse septa ; the polypary is either branched 

 or massive. Ehrenberg places this genus near 

 Astraea. The sp;;cies known arc all fossil. Fig. 3831 

 represents Favosites Gothlandica, Goldfuss : « and 

 b, two specimens ; c, nuclei of the tubes ; d, tubes, 

 magnified ; e, portion of a vertical section. 



Another genus, also fossil, is termed Terebellaria. 

 It is branched, with small oval cells arranged in 

 quincunx order on the surface of the polypary. 



Fig. 3832 represents a beautiful sjiecies, Tere- 

 bellaria ramosissima, found in the oolite of Caen, 

 and also near Bath. 



Another form, in which the cells are rounded and 

 poriform, is represented by Stromatopora, of which 

 the Stromatopora subconceiitrica. Fig. 3833, isfound 

 in the transition limestone. The polypary is hemi- 

 spherical, formed alternately of solid and porous 

 layers, superimposed upon each other. Relerring 

 to Fig. 3833 : a shows the surface of a mass, re- 

 duced ; i, a vortical section, reduced; c, a portion 

 highly magnified. 



The genus Heteropora presents us with fossil 

 species of a branched character, in which the cells, 

 of different sizes, some large and some small, are 

 dispersed over the whole surface. Fig. 3834 repre- 

 sents the Heteropora cryptopora, from the chalk of 

 Maestricht. 



We shall conclude this sketch of the MilleporidjB 

 with the genus Hornera, of which there are both 

 recent and fossil species. The polypary is fragile 

 and branched, and the cells, which are prominent 

 and arranged nearly in quincunx order, are disposed 

 over the inner face of the branches, the opposite face 

 being furrowed. The polypes have not been ob- 

 served. Fig. 3835 represents the Hornera frondicu- 

 lata: a, the natural size ; b, the upper; c, the lower 

 surface of a branch, magnified. 



Before leaving these stony corals, it may not be 

 out of place to give a brief attention to coral reefs 

 and islands, respecting which so much has been said 

 by voyagers in the Southern Ocean. And here we 

 must refer to Mr. Darwin's admirable work, in which 

 he gives the results of his own personal observations. 

 Among the Coral islands, consisting of rings encir- 

 cling a lagoon, may be noticed the Keeling orCocos 

 islands, about six hundred miles from the coast of 

 Sumatra ; one of these, Whitsunday Island, says Mr. 

 Darwin, will serve to give an excellent idea of the 

 general appearance of an annular Coral island, en- 

 circling a placid lagoon, and covered with cocoa- 

 nut trees, which in process of time have clothed 

 what was once a bare and water-washed reef. With 

 reference to Keeling Island he says, " The annu- 

 lar reef of this lagoon island is surmounted, in the 

 greater part of its length, by linear islets. On the 

 northern or leeward side there is an opening through 

 which vessels reach the anchorage. On entering, 

 the scene was very curious and rather pretty ; its 

 beauty, however, being solely dependent on the sur- 

 rounding colours. The shallow, clear, and still water 

 of the lagoon, resting in its greater part on white 

 sand, is, when illuminated by a vertical sun, of a most 

 vivid green. This brilliant expanse, several miles 

 in width, is on all sides divided, either from the 

 dark heaving water of the ocean by a line of snow- 

 white breakers, or from the blue vault of heaven by 

 strips of land crowned at an equal height by the 

 tops of the cocoa-nut trees. As a white cloud here 

 and there affords a pleasing contrast with the azure 

 sky, so in the lagoon dark bands of living coral ap- 

 pear through the emerald-green water." Such is 

 the picture of a coral island, to which the waves 

 drift the germs of a tropical flora, to which sea-birds 

 repair, and build uninterrupted for centuries, till 

 man arrives and claims it as his own. 



Besides low annular islands encircling a lagoon, 

 there are reel's of coral encircling islands, at various 

 distances from the shore, such, lor instance, as that 

 of Vanikoio, where La Perouse was shipwrecked. 

 "The reef runs there at the distance of two and, in 

 some parts, three miles from the shore, and is sepa- 

 rated from it by a channel, leaving a general depth 

 of between thirty and (brty fathoms, and in one part 

 no less than fifty, or three hundred feet. Externally 

 the reef rises from an ocean profoundly deep.'' 



3G2 



