THE CYCLOPiEDIA; OR, UNIVERSAL DICTIONARY OF larts, ^cimct0, anli iiteraturt. BY ABRAHAM REES, D.D. F.R.S. F.L.S. S.Amer.Soc. WITH THE ASSISTANCE OF EMINENT PROFESSIONAL GENTLEMEN. ILLUSTRATED WITH NUMEROUS ENGRAVINGS, BY THE MOST DISTINGUISHED ARTISTS, IN THIRTY-NINE VOLUMES. VOL. XXXVII. LONDON Printed for LONGMAN, HURST, REES, ORME, & BROWN, rATERNOSTEK-Kow, T.C. AMDJ. KIVtNGTON, A. STRAHAN, PAYNE AND FOSS, SCATCHERD AND LETTERMAN, J. CUTHELL, CLARKE AND SONS, LACKINGTON HUGHES HAKDING MAVOU AND JONES, J. AND A. ARCH, CADELL AND DAVIES, S. nAOSTER, J. MAWMAN, JAMES BLACK AND SON, BLACK KINGSBl'I<^ PARP.UHY AND ALLEN, R. SC:lIOLEY, J. nOOTH, J. nOOKER, SUTTABY EVANCK AND l-OX, BALDWIN CRADOCK AND JOY, SHERWOOD NEELY AND JONES, R. SAUNDERS, HURST ROBINSON AND CO., J. DICKINSON, J. PATERSON, E. WHITESIDE, WILSON AND SONS, AND BHODIE AND UOWDINO. 1819. CYCLOPEDIA I-': .3 OR, A NEW UNIVERSAL DICTIONARY OF ARTS and SCIENCES. VERMES. VERMES, ill Anatomy and Phyftolagy. We have ex- plained, underCjLASsiFicATioN, the objections to which the Linnsean clafs of Vermes is hable, confidered as one of tlie great divifions of the animal kingdom ; and we have propofed, in place of it, an arrangement grounded on the dif- tinftions of anatomical ftrufture, and therefore better fuited to the puipofes of comparative anatomy, as well as more conformable to natural method. As the anatomical defcrip- tion of tlie Mollusca (which order includes mod of the I.innspan vciim-a) toiild not be prepnrpd in time to appear under that word, it has been deferred to the prefent article, which will include alfo an account of the clafles Vermes andZooPHYTA. In his " Handbuch der Naturgefchichte," Blumenbach retains the Linnajan term Vermes, dividing the clafs into, I. Intcftina ; II. MoUufca ; III. Teftacea ; IV. Cruftacca ( Echino-dermata, Cuvier) ; V. Corallia (Zoophytes of mod naturali(ls); and VI. Zoophyta (chiefly microfcopic animals and the animalcula infuforia). In the following article we fhall employ the terms Mol- lusca, Vermes, and Zoophyta, not in the acceptation in which they are ufed by Linnseus or Blumenbach, but as they are explained in the article Classification; — the fame fenfe in which they arc ufed by the French naturahfts generally, and by Cuvier particularly, in his moft valuable and ufeful works, the " Tableau clementaire" and " Le- mons d' Anatomic comparec." When, ill defcending along the fcale of living beings, we arrive, after the clafs of fifhes, at the in vertebraf animals, or fuch as have no vertebral column, we enter on an immcnfe fcrics of various crc.itures, the moft numerous, and at the fame time the moft curious and intercfting in refpeft to the difference of their organization and f.icultics. At this point in the fcale, the vertebral column i» anni- hilated : as this column is the bafis of the fkclcton, the latter Vol. XXXVII. no longer exifts ; and confequently the moving parts no longer have their points of aftion on internal organs. Moreover, no invertebral animij breathes by means of cellular lungs : none have any vocal organ, nor confequently voice. They appear, at leaft for the moft part, not to have true blood ; that is, not to have a fluid undergoing a true circulation, and pofleffing, as one of its eflential charafters, the red colour. It would be an abufe of words to call the colourlefs fluid, which moves (lowly in the cellular fub- ftance of polypes, blood. We might as well give that name to the fap of vegetables. This conftant and ftriking difference of colour in the nutritive fluids has been adopted, by fome zoologifts, as the bafis of their firft great divifion of the animal kingdom. The primary divifion into red-blooded and white-blooded correfponds with that into vertebral and invertebral .mimals. The eye has no iris in invertebral animals. They have i>0 kidney. In the vertebral clafles, and particularly in the firft, or that of moft complicated and perfeft organization, all the eflential organs are infulatcd, occupying diftindl and fepa- rate fituatioiis ; in the invertebral, they are all brought to- gether. In his " Tableau elementairc," Cuvier introduces us to the Zoophytes as the laft or moft fimplc of the anim.il king- dom in their organization and faculties. The MoUufca pofiefs nearly the fame apparatus of organs for digeftioii, circulation, refpiration, and feiifation as red-blooded ani- mals ; and they even come very near in thefe points to filh. Infcfts, occupying a lower rank in the fcale, have no diftinA circulation, and refpirc by trachea:. Yet tlicy polTefs a fpin.il marrow, nerves, and organs of fenfe. In moft vermes wc recognife analogous parts, and tluy probably cxift in all. But, in the zoophytes, wc no longer difcern thefe organic B apparatufee : 414078 VERMES. apparatufes : there are, in a few, barely digeftive vifcera, and fome indications of refpiration. They have no circula- tion, no nerves, no centre of fenfation : each part of the body feems to imbibe immediately the materials of its nu- trition, and to poffefs, within itfelf, the power of fenfation. Hence moft of thefe animals have very ftrong reproduftive powers, quickly reiloring injured or loft parts. Some of them indeed are multiplied by a fimple divifion, bke plants. There are however different degrees in this fimplicity, which is common to all. We pafs fucceffively from beings, which have feet, tentacula, hard and foft parts, and diftincl vifcera {viz. the Echino-dermata), to others, whofe whole body is a gelatinous mafs varioufly (haped (Meduf^s), or, when ex- amined with the moft powerful microfcope, prefents an ap- parently indivifible atom (Infuforia). Stagnant water, infufions of vegetable fubftances, the recent feminal fluids of animals, &c. teem with animated points, round, oval, or of other fip\ires, with or without a fmall appendix forming a tail, only vifible, for the moft part, by means of ftrong magnifying powers. In the arrangement of LamarcK thefe creatures form a diftinft clafs, with the name Infuforia. As they are merely microfcopic objefts, we can only fay of them, that they are minute, gelatinous, femitranfparent points, in fome of which more opaque fpots are vifible, homogeneous, irri- table throughout, and contrading in every direftion ; con- fequently changing their form frequently, but generally affuming, when at reft, a determinate figure in each fpe- cies. We confider that thefe little bodies, which are mere animated points, and conftitute, if we may ufe fuch an ex- preffion, the ultimate term of organization (ultimate at leaft to our means of refearch), are nouriftied byabforption from their whole furface, and are probably excited by the fur- rounding influences of caloric, electricity. Sec. Thus they refemble vegetables, which live by abforption, executing no digeftion, and performing organic motions in confequence of external excitation. But the infuforia are irritable and con- traftile, and execute fudden motions, which they can repeat : this charafterizes their animal nature. The genus Monas of Cuvier, or Chaos of Blumenbach, includes the fimpleft known animals. The latter author di- vides his Chaos into aquatile, infuforium, and fpermaticum, according as the animals are found in water, in vegetable infufions, or in animal femen. For a defcription of the latter, we refer to the article Generation ; fome of the former are noticed under Animalcule. The Volvox is a round, yellowifti or greenifh, gelatinous, and nearly tranfparent ani- malcule, which fwims round and round, and moves about without any vifible organs of motion. It (volvox globator) abounds in fummer in the water of marlhes, and then has a reddifti colour. In its interior we can diftinguifh globes fimilar to itfelf, which come out of its body, move about in the fame way, and are feen to contain other fmaller ones ; fo that the animal may be faid to be pregnant at once with feveral fucceffive generations. The volvox conflitlor is found ' in the water of dunghills, and moves by turning alternately to the right and left. It contains internally round mole- cules, which move about alfo. The appearance of thefe animalcules, their motions, and the multiplication of fome fpecies, lead us to afcribe them to the animal kingdom ; but doubts are entertained on the fubjeft. In that fenfe, at leaft, we underftand the remark of Cuvier, " On feroit nieme teniedecroire que plufieurs de ces aniniaux microfcopiques ne fe ferment que de la decom- pofition des mati^res foumifesa I'infufion." Tab. Element. p. 663. They who believe them to be animals, are again divided in opinion refpefting the mode of their produftion ; fome arguing from analogy that they are produced by generation of fome kind, while others admit of a fpontaneous origin, or what has been commonly called equivocal generation. Spal- lanzani made feveral experiments to determine this point. Long boiling accelerated the produdion of the animalcules ; which were alfo produced from the infufion of vegetable feeds burnt with the blowpipe. When boihng infufions were put into glals tubes, and thefe immediately hermetically fealed, no animalcules were produced. Eleftiicity, tobacco- fmoke, oleaginous, fpirituous, and corrofive liquors deftroy them. They will live a month in vacuo ; but are not pro- duced in that fituation. Spallanzani's Trafts on Animals and Vegetables. Refpefting this doftrine of equivocal generation, we may obferve, that the only argument in its favour is the indireft and unfatisfaftory one arifing from its oppofers being unable to (hew that the creatures in queftion are produced by a procefs of generation. The analogy of all nature, down to the minuteft infedls, which our microfcopes enable us to in- veftigate, affords a very ftrong prefumptive proof againft it, and leads us to conclude, that if our means of examination were more perfeft, we ftiould find that thefe creatures are produced and multiplied like all other animated beings. There are numerous other fpecies named after differences of form, or according to the circumftances under which they are produced. The Proteus has the fingular property of changing its form, almoft incefiantly, into every poffible modification of figure. The fmall animals found in vinegar and palle (Vibrio aceti et glutinis), generally called eels from their elongated figure, are almoft large enough to be diftin- guiflied by the naked eye. Freezing does not deftroy them ; but evaporation does, unlefs they are protefted by a little duft from the contaft of the air. It is faid that they change their llvin, that they have different fexes, and produce young ones alive in fpring, then lay eggs till autumn. The genera juft enumerated, viz. Monas, Volvox, Pro- teus, Vibrio, together with two other?, Burfaria and Kol- poda, make up the ord'.-r infuforia nuda of Lamarck ; that is, fuch as have no external appendices. He has a fecond order of infuforia appendiculata, including fuch infufion animalriiles as exhibit any prominent part like hairs or tail, &c. The feminal vermiculi, as they have been termed, (cercarix, Lamarck,) belong to this order, for they have a tail. It includes alfo the genus or family of the tricho-cercK and trichodce. We come next to animalcules a little more complicated in their ftrufture : they poffefs ftellated organs, confifting of fine ciliated proceffes lurrounding an opening, and fufcep- tiblc of motion, with the fuppofed objeft of drawing their prey towards the aperture. The following anitnals are formed by Lamarck into an order which he calls Polypi, and which we deem a very natural one. They are gemmiparous, or multiply by ftioots. They have a fmall elongated body, homogeneous, gelatinous, very irritable, poffefling wonderful reproduftive powers, provided at its upper end with a mouth, which is furrounded by rotatory organs, or radiated tentacula, and ferves as the entrance of an ahmentary cavity which has no other opening. This cavity is the only organ they pof- fefs ; it is ufually an elongated bag, feldom folded on itfelf, or poffefling any appendages. Such is the idea of a polype : when feveral of thefe little bodies are connefled together, and participate a common life, they compofe the animals of zoophytes. The VERMES. The idea, which fome have entertained, that the brain and nerves, the mufcular fyftem, &c. of which no trace can be difcovered in the polypi, neverthelefs exift, but are expanded and as it were melted down into the general mafs of the body, fo that every point is capable of fenfation, mufcular motion, &c. is a perfeAly gratuitous and impro- bable fuppofition. On this view, it would follow that a frefh-water polype (hydra) has all the organs of a perfeft animal in every part of its body, and confequently fees, hears, fmells, &c. at all points. Thus it would be a more perfeft animal than man, as each molecule would be equi- valent, in the complement of its organization and faculties, to an entire individual of the human fpecies. If we allow this to the polype, how can we refufe it to the monas, to vegetables ? The ftudy of nature teaches us in all cafes, that when an organ ceafes to exift, the faculty is no longer found. The polypi are very irritable, and are afted on by exter- nal influences. Light attrafts them towards the quarter whence it comes, as it does the branches, flowers, and leaves of plants. No polype purfues its prey ; but when a foreign body touches its tentacula, they ftop and convey it to the mouth ; it is fwallowed without difliinftion, digefted if fuf- ceptible of that procefs, otherwife rejefted. Lamarck objefts to the term zoophytes, or animal plants, becaufe thefe are truly animals, and have nothing of vege- table nature. The only relations between polypi and plants are in the fimplicity of their ftrufturc, in the conneftion of feveral polypi with each other, fo as to communicate by their alimentary canal, and form compound animals ; and in the external form of the maffes which thefe united polypi com- pofe, a form which for a long time caufed them to be taken for true vegetables, fmce they are often ramified nearly in the fame manner. Wliether polypi have one or more mouths, we muft always bear in mind that tliey lead to an alimentary cavity, that is, to an organ of digeftion which docs not exift in any vegetable. The wheel animal of Spallanzani is a remarkable fpecies of this kind (rotifer redivivus ; vorticella rotatoria, Grael.) It is found in ftagnant water, and in the fand of fewers and tiles. It has a tail, and is forked in front ; each portion bearing a kind of toothed wheel, which can be drawn in at pleafure. Internally an organ is perceptible with a flow and irregular motion, fuppofed to be a ftomacli. The name of redivivus was given to this creature from its remarkable property, pointed out by Spallanzani, of re- covering life after being long dried. This refufcitation will take place at the end of fome years ; but Spallanzani fays, that the animal muft be kept in the fand in which it is found. (See his Trafts. ) Baker (on the Microfcopc) makes a fimilar reprefentation with refpeft to the eels of blighted corn. The vorticcUas of Cuvier, polypes a bouquet, (Brachio- nus, Blumenbach,) have fmall organs, like fine hairs, coming out of their anterior extremities, turning about rapidly and inceftantly : their nature and ufe are unknown. Some have a tail ; others a thread-like peduncle. The latter are united in an arborefcent manner. They inhabit ftagnant waters, and are fo minute, that a mafs of them appears only as a fpot of film. They multiply by fimple divifion, one of the fmill bodies fplitting, and each half becoming an entire one. The botrylli, corini, and criftatellsc, or polypes a plumet of Cuvier, are allied to the latter : they poffefs tentacula or ciliated organs ; and are either fingle or coUefted into arbo- refcent maffes. In the frcfli-water polypes (hydra), the organizaliun is rather more complicated, and the fize of the animal increafes, fo that It is vifible with the naked eye. They are gelati- nous, femi-tranfparent, and therefore not eafily rccognifed by a perfon unaccuftomed to look for them'. Their body is elongated, fmall at one end, by which it is attached to fome aquatic plant, teftaceous animal, &c. and larger at the other. It confifts of a cavity terminating at the large end by a round orifice, furrounded by long tentacula. The animal indeed may be regarded as a ftomach, provided with inftruments for catching its food : the latter is the ufe of the tentacula. The fubftance of the body appears, under the ftrongeft magnifying powers, a mere jelly, with more opaque portions interfperfed. Blumenbach compares it to boiled fago. They hve on naiades, monocuh, and other fmall aquatic animals, which they feize with their tentacula, and convey into the ftomach, where they are digefted, and from which the refufe is rejedled by the fame opening. They perform locomotion, and feem very fenfible to light, although nothing like mufcle or nerve can be difcemed in them. Neither have any vcflels been feen in them : they are faid indeed to receive a tint from the food they take, fo that it muft pafs immediately from the ftomach into the organs. The moft furprifing circumftances, however, in thefe ani- mals, are their mode of multiphcation and their extenfive power of reproduftion. They propagate by buds from their own body- If cut into fix or more pieces, each be- comes a perfeft animal : they may be inverted, and the ex- ternal and internal furfaces will be changed and afiume each other's funftions. When they are partially divided in the longitudinal direftion, the feparated parts heal fo as to form two heads or tails, &c. See the article Polype ; alfo, Trembley Mem. pour fervir a I'Hiftoire d'un Genre de Polypes d'Eau douce, &c. ; Leid. 1744, 410. Baker's Natural Hiftory of the Polype ; Lond. 1743, 8vo. Rijfel Hiftorie der Polypen ; in the third volume of his Infeften- beluftigungen. Schaffer Armpolypen in den fiiflen Waf- fern um Regenlburg, 1754, 4to. From the frcrti-water polypes, there is an eafy tranfition to the animal of the Weft India iflands defcribed by Ellis, in the Phil. Tranf. vol. Ivii. tab. 19. fig. i, and in his Natural Hiftory of Zoophytes, tab. i. fig. i, under the name of aftinia fociata, or clufter animal flower. It is the zoanthe ii drageons of Cuvier, hydra fociata of Gmelin. It is of a tender flcftiy fubftance, confifting of many diftindl tubukir bodies, each of which fwells above into a fmall bulb : at the top of this bulb is the mouth, furrounded by one or two rows of tentacula, which can be extended or with- drawn at pleafure : in the latter ftate they look like circles of beads. Thefe bodies are connefted below to a firm fleftiy wrinkled tube, fticking fail to the rocks, and fend- ing forth other flefliy tubes, which creep along them in various direftions, and give origin to fimilar bodies rifing up irregularly in groups. Knobs are obferved on the ad- hering tube, from its infinuating itfelf into the inequalities gf the coral rock. When the animal is diftttted lengthwife, a large cavity is expofed, into which a tube opens from the mouth. From this tube eight fmall cords arife, continued to the lower part of the animal, where they feem to be loll in the flefliv bafis. The fmall polypi will appear to us more wonderful, and will more powerfully engage our attention, when we find that they produce all thofc marine fubftances, formerly called zoophytes, from a notion that they partook both of the animal and vegetable natures, and including corals, co- rallines, madrepores, millcporcs, fponges, &c. &c. So ac- tive are thefe mimilc creatures in fome parts of the ocean, B z that 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 VERMES. Thus, in a feapen of a fpan lonjr, there are at leaft above 500 of thefe polypes. (See Ellis, Zoophytes, p. 6. et feq. tab. 8.) They fwim about in the fea by a common motion produced by their numerous polypi ; and are re- markable for pofTeffing phofphoric properties ; hence one kind has been called pennatula phofphorea, and Linnaeus fays of it, " habitat in oceano, fundum illuminans." (Phil. Tranf. vol. liii. tab. 19. fig. i — 5.) The pennatula rubra, or Italian feapen, is alfo ilrongly phofphoric. Dr. Shaw ob- ferves of it, that on the coaft of Algiers it fends forth fo great a light in the night, that the filhermen can dillin- guilh the fi{h as they fwim by it, fo as to know where to caft their nets. See Phil. Tranf. vol. liii. p. zi. figs. 1, 2. The foft covering of the ftem of the feapens confifts ex ternally of a ftrong coriaceous membrane, and internally of a thinner membrane : the cavity of the latter is occupied merely by the bone or cartilage. Between the two mem- branes are innumerable yellowilh eggs, floating in a whitifh liquor. The fins are alfo compofed of two fl; mufcles, in the fubftance of which they are loft. Thefe nerves run in oppofite direftions, fo that they reprefent the figure of an X. The coat of thefe nerves is black, and very folid, fo that before the parts have been immerfed in alcohol, they appear like a fyftem of veffels. The nervous cord of the Earth-worm derives its origin from a ganglion fituated above the cefophagus : this ganglion is formed of two clofe, but very diftinft tubercles. It pro- duces a pair of fmall nerves proceeding to the parietes of the mouth, and two large cords, which embrace the cefopha- gus in the form of a collar : thefe unite to form the nervous cord, the origin of which therefore appears bifurcated. Three pair of fmall nerves are detached at this place : one from the cord itfelf, and the others from its lateral parts. They all proceed into the mufcles of the mouth. The nervous trunk is continued to the anus, along the inferior part of the inteftine ; its fize is not fenfibly diminiftied, and the contraftions are not very remarkable : there arc, there- fore, no real gangha. A pair of nerves arifes between each of the rings of the body ; thefe nerves pafs under the longi- tudinal mufcles, and difappear between them and the fl