VERMES. 



gated, without head, eyes, or articulated limbs. They have 

 no circulating veffels. No organ of fecundation has been 

 hitherto difcovered ; fo that fexual generation does not feem 

 to exift in them. The parts fuppofed in fome to be ovaries 

 feem to be mere colleftions of reproduftive molecules, which 

 require no fecundation. Their inteftinal canal is complete, 

 or poflefles two openings ; and the mouth conliUs of one or 

 more apparatufes for fucking. 



The clafs is divided into three orders ; viz. cylindrical, 

 veficular, and flattened worms, according to the form of 

 the body. 



The clafs of annclides or annulofa has a foft elongated 

 body, covered by tranfverfe rings, and no articulated limbs : 

 feldom a head or eyes. They have a knotted fpinal marrow ; 

 arteries and veins containing a fluid, which is generally red. 

 They breathe by branchias, which are fometimes external and 

 prominent, fometimes concealed. 



The clafs confifts of two orders : 



I. Annulofa crypto-branchia (having concealed branchiae). 

 Genera : Planaria. Hirudo. Lernasa. Clavala. Naias. 

 Lumbricus. Thalaflema. 



I I . Gymno-branchia ( having external branchiae ) . Genera : 

 Arenicola. Amphinomia. Nereis. TerebeUa. Amphitrite. 

 Sabellai"ia. Serpula. Spirorbis. Siliquaria. Dentalium. 



The moUufca have a mufcular heart, to which the nutri- 

 tive fluid is brought by the veins, and from which it is car- 

 ried out by the arteries ; they have organs nearly refembling 

 the gills of fi{h, in which the fluid is expofed to the in- 

 fluence of the furrounding element, and glands which pour 

 different fecretions into the alimentary canal. They have a 

 brain, nerves, and fome organs of fenfe ; but in the latter 

 there is more variety than in the other points. Their body, 

 or at leaft; their limbs have no bone in the interior ; but fe- 

 veral of them are inclofed in very firm, even ftrong cafes, 

 which are called (hells (teftae), whence the animals them- 

 felves have been denominated teftacea or fliell-fifli in common 

 language. Thefe are comprehended, together with the en- 

 tirely naked ones, under the name moUufca. 



They have white and very irritable mnfcles. They are 

 extremely tenacious of life ; moving after being cut into 

 feveral pieces, and reproducing very confiderable portions of 

 their body when dcftroyed in any way. Their fliiii is always 

 foft, and generally lubucated by a vifcous (ecretion : it is 

 very fenfiblc, and poflefles organs, called tentacula, capable 

 of elongation, for the purpofe of touchmg. None have 

 organs of fmclling, but there are eyes in feveral, and ears 

 in fome. The body is generally enveloped, or at leafl; co- 

 vered in great part by a membranous invcftment, called in 

 French manleau, which we fliall term the mantle. Several 

 have moreover a hard covering named a (hell, compofcd of 

 one or mgre pieces, called valves, and produced by calca- 

 reous matter tranfuding from the mantle. To this the body 

 is fixed by means of mufcles. Moll mollufca inhabit the 

 fea ; fome dwell in frcfli water, and others live in the 

 earth. 



Lamarck removes four genera from the mollufca, to con- 

 ftitute a diHinft clafs, wfiich he calls cirrhipedcs : thefe 

 genera are tubicintlla, coronula, balanus, anatifa. Their 

 principal dillingui(hing charafters are articulated arms co- 

 vered by a homy flcin ; two pairs of mandibles to the mouth ; 

 a knotted nervous cord. 



It appears from the preceding review, if we join to it the 

 confideration of the (Irufture of infefts, that the animals 

 with white blood, as they have been called, have not fo 

 many common characters as the red-blooded. Their chief 

 JiftinAions are of the negative kind, as the abfence of a 



vertebral column, and of an interior articulated flieleton, 

 &c. 



" Thus," fays Lamarck, " when we confider fucceflively 

 the various organic fyftems of animals, from the mofl; com- 

 pound to the moft fimplc, we (hall obferve a degradation of 

 the organization commencing even in the clafs which com- 

 prehends the moft perfeft animals, proceeding from clafs to 

 clafs, though with anomalies caufed by various circumfl;ances, 

 and terminating at lafl: in the infuforia. The latter are the 

 moft imperfeft, and moft fimply organized ; the degrada- 

 tion in them has reached its term, the organization being re- 

 duced to a fimple, homogeneous, gelatinous body, almoft 

 without confiftence, polfefTrng no diftinft organs, and fimply 

 formed of a very delicate tillue, which feems to be affefted 

 by the furrounding fubtile fluids. 



" We have feen each organ, even the moft effential, gra- 

 dually degenerate, become lefs diftinft, and at laft entirely 

 difappear long before we had reached the extremity of the 

 feries : and we may obferve, that it is principally in the in- 

 vertebral animals that the fpecial organs are obferved to be 

 annihilated. 



" Before we quit the divifion of vertebral animals, great 

 changes are perceived in the perfeftion of the organs, and 

 even fome of them, as the urinary bladder, the organ of the 

 voice, the eye-lids, &c. difappear entirely. The lung, 

 which is the molt perfect apparatus for breathing, dege- 

 nerates in reptiles, ceafes to exift in fiflies, and is not 

 found in any invertebral animal. The (Iveleton itfelf, which 

 furniflies the bafis of the four hmbs polfefled by moft verte- 

 bral animals, begins to decline, particularly in reptiles, and 

 ends altogether in fifli. 



" But in the invertebral animals, we fee the moft important 

 parts annihilated, one after the other : the heart, the brain, 

 the branchiae, conglomerate glands, circulating velfels, the 

 organ of hearing and of fight, thofe of fexual generation, 

 and even thofe of fenfation and motion. We fliould feek in 

 vain among the polypes for the flighted trace of nerves or 

 mufclea : irritability alone fupplies the place of fenfation and 

 voluntary motion. AH the motions of a polype are the re- 

 fult of external excitation. Put a frefli-water polype 

 (hydra) in a glafs of water, and place this glafs in a cham- 

 ber, which receives light from one quartir only. It will 

 flowly move itfelf towards the part on whicli the light falls, 

 and will remain there. Vegetables turn themfelves towards 

 the light in an analogous manner. 



" Undoubtedly, wherever a particular organ no longer ex- 

 ifts, the faculty which it exercifed teafes alfo : the latter is 

 alfo more obfcure in proportion to the deterioration of the 

 organization. Infedts are the laft, in the fcale of animated 

 nature, poflelTing eyes ; we have reafou to fuppolc that 

 they fee very obfcurely, and make but httle uie of their 

 eyes. 



" This degeneration may be obferved, even in tlic nature 

 and confiftence of the efl^ential fluids, and of the flefli of ani- 

 mals. The blood and mufcles of the mammalia and birds 

 are the moft compound and animalizod of .animal produc- 

 tions. After fifti, thefe fubftances are progrelTively changed 

 to fucli a degrte, that in the foft radiant animals, in the 

 polypi, and particularly in the infuforia, the nutritive fluid 

 has merely the colour and confiftence of water, and the flefli 

 is a foft jelly, fcarcely animalized." Philofophie Zoolo- 

 gique, torn. i. p. 212, et fcq. 



The following Table, extrafted from the fame work of 

 Lamarck, p. 277, ct feq. exhibits the invertebral animals, 

 arranged according to their ftruftui-c, willi tiieir princi- 

 pal charafters, in a progrcflive feries, from the moft fimple 

 upwards. 



Animals 



