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<ins ; the outer 

 ftrong and leathery, the inner thin and clear. The cylin- 

 drical part of the fuckers is formed in the fame way, except 

 that their outward (kins are foftcr. Both the fins and 

 fuckers are hollow ; fo that the cavity of the fuckers may 

 communicate with their fins, as their cavity does with the 

 trunk. 



See an account of the feapen or pennatula phofphorea 

 of Linnseus ; likewife a defcription of a new fpecies of fea- 

 pen, found on the coaft of South Carolina, with obfcrva- 

 tions on feapens in general, by J. Elhs, in the Phil. Tranf. ' 

 vol. hii. with three plates reprefenting various fpecies, with 

 magnified views of the fins and polypes. 



The lithophytes are zoophytes with an axis or bafis of 

 a ftony fubttance, in which receptacles for polypi are exca- 

 vated. The madrepores and millepores belong to this di- 

 vifipn. See Elhs's Zoophytes, tab. 23. for views of the 

 millepora truncata, in which the polypes are feen magnified. 

 They are fo numerous in fome feas, as to form entire 

 iflands : feveral of thofe in the South-fea are a mere con- 

 geries of madrepores. 



The lad kind of zoophytes have a fpongy friable or 

 fibrous fubftance for their bafis, covered by a flelhy incruf- 

 tation, which fometimes contains polypes. There are only 

 two genera ; "viz,, alcyonium and fpongia. The interior of 

 the latter is hght, friable when dry, compofed of fine, di- 

 verging fibres. The animal covering is a foft incruftation, 

 without calcareous particles, which becomes coriaceous by 

 drying, and is pierced with cells from which the heads of 

 polypes ilfuc-. See EUis in the Phil. Tranf. vol. liii. tab. 20. 

 figs. 10. II. and 13. 



Whether the fponges are animals, is dill doubted even by 

 good naturahfts : at all events, they polfets the charafters 

 and faculties of animals in the lowell degree. They confift 

 of a more or lefs denfe and flexible fibrous tifl"ue, covered 

 in its recent ftate by a femifluid and thin kind of animal 

 jelly. Regularly formed round apertures are obferved, 

 fometimes pierced in flightly prominent papillae ; but no 

 polypes itfue from thefe, nor has a[iy thing of the kind ever 

 been feen in them. The only circumftance mentioned about 

 them, that can be deemed a fign of life, is a (light and 

 hardly perceptible contraftion or flirinking, when they are 

 torn from their fituation. After their death, the animal 

 jelly diflolvs and is removed, and tiie fibrous bafis alone is 

 left. See EHii on the Nature and Formation of Sponges, 

 Phil. Tranf. vol. Iv. pi. 10 and 11. 



Next to the polypes, whether exifting fingly and un- 

 covered, or connected with thofe conilruftitfiis which con- 



ftitute the zoophytes, we may place, in refpeA to fimplicity 

 of (IruAure, the adinix and medufse. The former polfefs a 

 coriaceous body, with confiderable power of contraftion, 

 which enables tlie animal to change its figure very remark- 

 ably, from a half fphere, when the mouth is (hut, and the 

 tentacula withdrawn, to a cylinder when it is open. It ad- 

 heres by a circular diik to the fand, rocks, &c. The 

 oppofite end forms a mouth, furrounded by feveral rows 

 of long, conical, and moveable tentacula, which can be 

 withdrawn or extended at pleafure. The mouth is round, 

 and leads ftraight into a cylindrical ftomach, with rugous 

 fides. They live on fmall crabs principally, which they 

 feize and envelop with their tentacula. The refufe is re- 

 jefted by the fame palfage. Between the parieles of the 

 ftomach and the fliin there is a vail: number of very fine in- 

 teilines, interwoven with each other, of which the commu- 

 nications and ufes have not been found out. 



The aCliniae are famous for their reproduftive powers. 

 When cut in two, each part becomes a perfeA annnal. The 

 tentacula and other parts are eafily reftored. The young 

 aftini<e are born ahve, either at the mouth or through the 

 fide of the parent ; in the latter cafe the cicatrix foon clofes. 

 They move fometimes on their bafis, fometimes on the ten- 

 tacula. 



Lamarck's clafs of polypi terminates with the aftinii. 

 It includes the following orders : 



I. Polypes rotiferes ^ wheel-bearing), having ciliated and 

 rotatory organs round the mouth. Urceolarise. Brachioni. 

 Vorticellae. 



II. Polypes a polypier, — polypes connefted with hard 

 fubftanccs ; having radiated tentacula about the mouth, and 

 connefted to a hard fubftance, which does not float loofe in 

 the water. 



1. With membranous or horny polypier, without any dif- 

 tinft cortex. Criftatella. Plumatella. Cellularia. Sertu- 

 laria. Fluftra. Cellepora. Botryla. 



2. Polypier with a horny axis, covered by an incruftation. 

 Acetabulum. Coralhna. Spongia. Alcyonium. Anti- 

 pathes. Gorgonia. 



3. Polypier with an axis partly or entirely ftony, and 

 covered by a bark-like incruftation. Ifis. Corallium. 



4. Polypier entirely ftony, and without incruftation. Tu- 

 bipora. Lunulite. Ovalite. Siderolite. Orbalite. Al- 

 veolite. Ocellaria. Efchara. Retepora. Millepora. Aga- 

 rica. Pavonia. Meandrina. Aftrea. Madrepora. Caryo- 

 phyllia. Turbinolia. Foiigia. CycloUte. Daftylopore. 

 Virgularia. 



III. Polypes flottans ; loofe polypi. 



Polypier loofe, floating in the water, having a horny or 

 ofTeous axis, covered by a fle(hy inveftment, to which all the 

 polypi are connefted : radiated tentacula round the mouth 

 of the latter. Funiculina. Veretilla. Pennatula. En- 

 crinus. Umbelhilaria. 



IV. Naked polypi ; mouth with radiated tentacula, often 

 multiplied ; no polypier. Pedicellaria. Corina. Hydra. 

 Zoanthus. AAinia. 



The fubftance of the medufx is tranfparent and gelatinous 

 (whence their common name of fea-blubber), a d almoil 

 entirely deftroyed by evaporation or boiling. In the ftate 

 of reft, their body reprefenls the fegment of a fphere, with 

 the convexity fmooth, and the oppofite fnrlar<- furni(hcd 

 with various tentacula- Coloured lines are oblerved in 

 their interior, but nothing which indicates circulation. To- 

 wards their edges, however, numerous veftels are obferved, 

 communicating appivcntly with the alimentary cavity. They 

 inhabit the ocean, fwimming very well by rendering their 



body 



