VERMES. 



that their conftiiiftions form the bafis of new iflands, con- 

 ftitute extenlive and dangerous reefs, block Up harbours, 

 create /heals, &c. All which effefts are produced by ani- 

 mals not greatly exceeding in bulk the frefh-water polype. 



It has been repeatedly found in the Weft Indies, that 

 wrecks become covered univerfally and thickly with madre- 

 pores and other corals within three-quarters of a year. The 

 formerly excellent harbour of Bantam is now almoft entirely 

 occupied by corals. Several volcanic ifles of the South-fea, 

 and fome even of the Weft Indian, as for example Bar- 

 badoes, are coated over with coral. The dangers to navi- 

 gators from great coral banks rifing out of the bottom of 

 the fea, in unknown trafts, may be illuftrated from what 

 Cook and FUnders experienced on the coafts of New 

 HoUand. 



Thefe produftions were formerly defcribed with vegeta- 

 bles, and they will be found fo clafled by Toumefort : their 

 vegetable nature was even defended by Pallas. Our coun- 

 tryman Mr. Elhs has the honour of demoriftrating that they 

 belong to the animal kingdom, and of fhewing the animals 

 by which they are formed. See his papers, accampanied by 

 plates, in the 48th, 49th, 50th, 53d, 55th, and 57th vols, of 

 the Phil. Tranf. ; alfo his admirable works, " Natural Hif- 

 tory of CoraUines," &c. Lond. 1755, 4to. ; " Natural Hif- 

 tory of many curious and uncommon Zoophvtcs," &c. 1 786, 

 4to. See alfo Donati della ftoria Naturale Marina dell' 

 Adriatico ; Venez. 1750, 410, ; Cavolini Memorie per fer- 

 vire alia ftoria de Polipi Marini ; Napol. 4to. 



The animals belonging to thefe fubftances may be called 

 compound polypi. The flefhy malFes, which are differently 

 circumftanced in different cafes, exhibit numerous projeft- 

 ing heads, each of which has a mouth with radiated tenta- 

 cula. Thefe heads may be either extended or withdrawn. 

 Thus all the polypi are connefted into one mafs, which is 

 increafed by (hoots. In ftrufture, thefe compound polypi 

 do not differ from the fimple ones, fo far at leaft as our pre- 

 fent knowledge of them goes. 



Some zoophytes confift of a horny tube, branching out 

 varioufly, and hollow internally. The axis of thefe zoo- 

 phytes is occupied by a ftem of animal fubftance, and at 

 each of its branches a polype projefts. The horny covering 

 probably grows as the fhells of the teftacea do : and we 

 may fuppofe, that the tentaculated heads of the animal 

 ferve to procure it nourifliment. The flofcularia is of this 

 kind ; the animal is not very intimately connefted to the 

 tube. 



The tubularia occurs in frefh water as well as in the fea ; 

 there is a horny tube, fometimes fimple, fometimes ramified. 

 The polype at the end exhibits tentacula, or a bundle of 

 hairs like a pencil. The capfularia and fertularia are of the 

 fame kind. 



In other inftances, each polype, inftead of being con- 

 nefted to a common ftem, is contained in a horny or calca- 

 reous cell, with thin fides. In thefe there is not the fame 

 direft communication as in the former genera. Each polype 

 is infulated, or, if they communicate, it muft be by very 

 fine filaments, traverfing the cells. 



In thefe and fome other of the zoophytes, veficles are 

 occafionally feen, and have been fuppofed to be ovaries : the 

 latter opinion, however, is inconfiftent with the views 

 entertained at prefent. CeUularia, fluftra, and corallina, 

 exemphfy this : though, with refpeft to the latter, it muft 

 be obferved, that its animals have not yet been demon- 

 ftrated, and its pores are fo fraall, that they muft be ex- 

 tremely minute. 



The zoophytes which have an axis of foUd fubftance, 

 covered by a foft fleftiy layer, with hollows, which con- 



tain tentaculated polypi, have been called cerato-phyta. The 

 axis is fometimes ligneous or horny, or ftony, and covered by 

 a flefhy fubftance capable of contrafting. In this there 

 are numerous hollow tubercles, from which there are pro- 

 jefted and withdrawn at will, heads, or rather tentaculated 

 mouths formed like polypi, all belonging to the fame animal, 

 like the branches of a polype : that is, the foft fubftance co- 

 vering the folid axis is to be regarded as the animal, of which 

 thefe are fo many mouths. It has the power of extending 

 itfelf to form a bafis of adherence to folid bodies. We alfo 

 obferve it extending over and forming a new ftratum of 

 coralline matter, inclofing foreign bodies that may be at- 

 tached to the axis. That the coralline axis is formed by 

 the fielhy covering cannot be doubted ; we perceive in it 

 concentric ftrata, indicating its fucceflive depofitions, and 

 the furface is marked by longitudinal lines correfponding to 

 the figure of the animal covering. When the trunk of the 

 coralline tree contains ligneous or vegetable matter, pro- 

 bably this is an extraneous body, on which the coral is 

 depofited. The branches are produced by an elongation 

 of the foft flefh, which forms them in its interior : but 

 their ftrata are not continuous with thofe of the trunk, as 

 in the cafe of trees. 



Cuvier (Tableau elementaire, p. 671.) ftates, that the 

 nourifliment taken by any of the polype heads is converted 

 to the ufe of the whole animal ; to which, alfo, he afcribes 

 a common will, as evidenced by its extcnfion for the purpofe 

 of adhering to furroundmg objefts. We know no fafts 

 concerning the ftrufture of the animal covering, at all fuffi- 

 cient to warrant thefe ftatcments. 



The gorgonia nobilis (ifis nobilis), or red coral, is an ex- 

 ample of this ftrufture. The axis is the compaft ftony 

 fubftance, of the hardnefs of marble, of which coral orna- 

 ments are made. The flefliy covering is of a bright red, 

 containing calcareous molecules, which form a kind of in- 

 cruftation when dried, and exhibiting numerous cavities in 

 which polypi are lodged. Each of thefe has eight denticu- 

 lated tentacula. The antipathes and ifis belong to this di- 

 v'fion. See the excellent plates of Ellis in the Natural Hif- 

 tory of Zoophvtes, exhibiting all the fafts above enumerated ; 

 particularly tab. 3. fig. 1 — J. for various views of the ifis 

 hippuris, or black and white coral : tab. 1 1, gorgonia flam- 

 mea : tab. 12. figs, i, 2. gorgonia ceratophyta : tab. 13. 

 '^g^- 3' 4- gorgonia peftinata : tab. 14. figs, i, 2. gorgonia 

 briareus : fig. 3. gorgonia pinnata. 



The pennatula, or fea-feather, belongs alfo to this divifion, 



and it is remarkable among the marine zoophytes, as being 



. unattached, and poffeffing the power of locomotion. All the 



others are fixed by their trunks or bafes to fome other ob- 



jeft, as rocks, fliells, fea-weed. Sec. &c. 



The pennatula refembles a feather, and confifts of a fliaft 

 and barbs. The former is cartilaginous and covered by a 

 flefliy layer ; from which, at its fmaller half, forty, fixty, 

 or more curved arms proceed on both fides, like the barbs 

 of a feather. Ten, twelve, or more fmaller proceffes are 

 continued from one edge of each of thefe primary barbs ; 

 and in each of thefe is contained a deHcate gelatinous polype, 

 with eight tentacula. 



" The ftem of the fuckers of this animal," fays Mr. EUis, 

 " is of a cylindrical form : from the upper part proceed eight 

 fine white filaments or claws to catch their food ; when they 

 retreat on the alarm of danger, they draw themielves into their 

 cafes, which are formed like the denticles in the corallines ; 

 but here each denticle is furniflied with fpiculse, which clofe 

 together round the entrance of the denticle, and proteft this 

 tender part from external injuries." Phil. Tranf. vol. hii.. 

 p. 424. 



Thusj 



