REPTILES. 



animals, compelled by their orjrans of motion to pafs the 

 whole, or nearly the whole of their life in water, can abfo- 

 lutely breathe air only. 



All the reptiles to whom Linnxus fubfequently transferred 

 this name of amphibious animals, are finiilarly circumftanced 

 in their adult Hate ; they can only breathe air, whether they 

 live conllantly in this element, as the lizard kind, or betake 

 themfelves, for a longer or fliorter period, to the water, as the 

 frogs and falanianders. On the otlier hand, the cartilaginous 

 fifhes, wliicli this fame naturalilt had joined to the reptiles, 

 like all other filhes, can only breathe by the intervention of 

 water ; they liaveonly gills ; and it is by having reprcfented 

 as lungs the forked fwimming bladder of fome of them, that 

 Dr. Garden caufed the miltake of Linnxus. 



The larvx or tadpoles of the batracian reptiles only, that 

 is to fay, of tlie falamandcrs and frogs, the tree-frogs and 

 toads, have both branchix and lungs ; breathe, at leaft. for a 

 certain time, both the air in its elalUc itate, and that which 

 is contained in water ; confequently participate equally the 

 nature of aerial and aquatic animals ; and may, therefore, 

 without impropriety, bear the name of amphibious in its 

 moll ftrid acceptation. But with thefc it is only a tranfi- 

 tory, and with fome perhaps only a momentary Hate. As 

 their lungs are developed, their branchix arc obliterated, and 

 they entirely lofe the latter, often even before reaching their 

 full fize, and particularly before they are capable of repro- 

 duiftion. Such, at leall, is the refult of oblervations on all 

 the tadpoles of thefe climates, on all which it is poffible to 

 follow in their various developements. 



But naturalifts have ohfervcd three other animals, uniting, 

 like our tadpoles, the two kinds of refpiratory organs, not 

 appearing to lofe any of them at any epocha of their lives, 

 and of fuch form and fize, that it is faid in the countries 

 which they inhabit, no perfeit reptile is known, of which 

 they could be the larvs. Are thefe creatures perfeft ani- 

 mals — true permanent amphibia? Should they be con- 

 fidered an intermediate clafs between reptiles and fifhes ? 

 We proceed to examine this queflion, obferving, in the firit 

 place, that the Hrufture of the circulating organs in the 

 common tadpoles, which has been defcribed in a former part 

 of this article, mull be kept in view as a point of com- 

 parifon. 



Anatomy of the Siren Laeerlina — This animal is common 

 in the rivers and marfhes of South Carolina, and is remark- 

 able for poffefTing only the fore feet. Dr. Garden fent an 

 individual to Linnxus, accompanied with a defcription, in 

 which he mentioned the fimultaneous exiftence of branchix 

 and lungs, and declared that there is no falamander in Caro- 

 lina large enough to have been produced from the firen. 

 Hence Liniixus determined to ellablifh for it a particular 

 order of reptiles, the amphibia meantcs. Nearly at the fame 

 time it was defcribed in the Philofophical Tranfaftions by 

 Ellis, whofe defcription was accompanied with an anatomy 

 of the animal by Mr. J. HuHter. Yet feveral naturahfls 

 Gontelled the refult of thefe examinations. Pallas, Her- 

 mann, Schneider, I and others, confidcred that it might be a 

 larva. Camper, on the faith of an imperfect fpecimen, in 

 which no lung could be found, concluded it was a fifli, 

 (Kleine Schriften, torn. iii. pi. i. p. 20.) ; and Gmeliu, 

 on his authority, clafTed it among the eels. 



Cuvier has had an opportunity of diffefting and de- 

 fcribmg it. His account, which fettles the difputes fatif- 

 faftorily, is contained in the Recherches already quoted, 

 and has furnifhed the materials of the following defcription. 

 The fafts are reprefcnted in the nth and 13th plates of the 

 firll volume of Humboldt's Recueil d'Obfervations de Zoo- 

 logie et d'Anatomie comparee. The length was half a metre, 



I 



but it readies fometimes between 30 and 40 inches. The 

 body is much Hke that of an eel. The anus is at 1 5 centimetre.-^ 

 from the pollcrior extremity. The iiead is not feparated 

 from the body by a neck : it is rounded, and terminated by 

 an obtufe fnout. The mouth is fm?ll, and the lips, which 

 are not confiderable, are not fupported by any bones, as 

 they fometimes are in fifhes. The noftrils are two fmall 

 holes near the edge of the upper lip. The eyes are placed 

 above the angle of the moutli : they are round, fmall, with- 

 out eye-lids, and only vifible becaufe the fkin, in palling 

 over them, becomes' tranfparent. You may lltin the head, 

 like that of an eel, without injuring the eye-ball. 



The openings of the gills are three vertical flits placed in 

 fucceflion behind the head : through them the water from 

 the mouth is difcharged. But there are no gills within, as 

 in the lamprey for example ; although Gi'rden, Ellis, and 

 Camper fuppofed it. The only branchix arc three tufts 

 or fingers, attached to the fuperior angle of the flits, to 

 which Ellis and Garden gave tlie name of opercula, but of 

 which Linnxus recognized the true nature. There arc 

 furely only three on each fide, of which the firfl is the 

 fmallefl, and the third the largcfl. The different flatements 

 concerning their number, which embarrafied M. Schneider, 

 arife from the name having been given to different parts. 

 For example, Linnxus, who rightly deemed tlie tufts to be 

 branchix, reckons three, without opercula (branchia ad 

 latera colli utrinque tria, exferta) ; but Card n, who con- 

 ceived that the branchix were connefted to the arches, fays 

 there are four, with three opercula, or one operculum of 

 three lobes. 



Each of the tufts confifls of a large flefiiy and conical 

 pedicle, of which the inferior edge is divided into two rows 

 of appendices, which are themfelves again twice divided in 

 the fame manner. The animal muft have the power of 

 moving thefe branchix in every diredlion : the net-work of 

 branchial veffels is expanded on their ramifications. 



The fore feet, fhort and flender, are placed a little be- 

 hind the branchial apertures. There are four fingers, of 

 which the lall phalanges are pointed, but not furnifhed with 

 nails. There is not the fmallefl appearance of fcales on the 

 fl<iii. 



OJleology. — Although the individual examined by Cuvier ■ 

 had not reached its full fize, ofTification was confiderably 

 advanced. The cranium, lower jaw, and fpine, were per- 

 fectly olTified. On the large bones of the arms there were 

 epiphyfes, and the fcapula was almoil entirely cartilaginous. 

 The latter bone remains conllantly in this ftate in the fala- 

 manders. The branchial arches were entirely cartilaginous, 

 and probably continue fo, as no point of offification could 

 be obferved, although the os hyoides and its branches were 

 already almoft completely hardened. 



From the head to the end of the tail there are ninety ver- 

 tcbrx : the anus is oppofite to the forty-fifth, yet it is far 

 from being oppofite to the middle of the body, becaufe the 

 vertebrx of the tail, particularly towards its end, are much 

 fmaller than the others. The land falamander has thirty- 

 eight, and the aquatic about forty. The pelvis is fufpended 

 oppofite to the fifteenth or fixteenth, in the former ; to the 

 fourteenth or fifteenth, in the latter. There is not the 

 fmallefl veflige of pelvis or hind leg in the iiren : there is 

 not even any germ of thefe parts, although they exift in 

 the tadpole at all ages. It is, therefore, very certainly 

 never deilined to have hind legs. There is a kind oi im- 

 perfeft pelvis, even in the ophifaurus (anguis ventralis, 

 glafs-fnake), a true ferpent, though analogous to the 

 lizards in fome points, but never poffefCng hind legs. 



Eight vertebrx only of the firen, from the fecond to the 



ninth, 



