REPTILES. 



ninth, fupport fmall ribs, or rather very fliort falfc ribs. 

 In the land falamander there are twelve or thirteen, and in 

 the aquatic eleven. Thefe fmall ribs, lolt among tlie 

 inufcles, are only obferved in the genur, of ferpenls called 

 cascilia, where they exift in great number. 



The individual vertebrce are very dillerently fhapod from 

 thofe of falamanders, frogs, and cxcilia. Tlie body is ter- 

 minated before and behind by a hollow cone fdled with car- 

 tilage, which unites it to tiie adjoining bones, as in filhcs. 

 There is a fmall longitudinal prominence below ; and above, 

 a crifta holding the place of the fpinous procefs, and bifur- 

 cated behind. The four angles of the fuperior furface are 

 occupied by the articular apophyfes, of which the anterior 

 have their articular faces turned upwards, and the pofterior 

 downwards. The tranfvcrfe proccHes are formed of two 

 triangular plates : one, inferior and horizontal, comes off 

 from the whole fide of the body of the vertebrae ; the other 

 flants backwards, and reaches from the anterior articular 

 procefs to the pofterior edge of the preceding. At the ex- 

 treme point of their union we find the furface to which the 

 rudiment of rib is articulated, in thole vcrtebrx which have 

 ribs. 



None of the alVcd genera refemble the firen in the form 

 of the vertebrie ; and their fingular (liape would alone be 

 fufhcient to authorife us in conftituting a feparate genus for 

 this animal. The head leads equally to the lame conclufion, 

 being entirely different from that of the falamander, and 

 other reptiles. The noftrils, finiply excavated at the fides 

 of the fiiout, do not penetrate into the mouth : neither the 

 orbit nor the temporal fofia is clofed below. Hence the 

 upper jaw-bone does not form a complete bony circle ; its 

 anterior part only is formed by the intermaxillary bones, 

 and has no teeth. Thus the firen has only palatine teeth 

 attached to the two plates, and not implanted in the palate. 

 The prominence, having the furface for the articulation of 

 the lower jaw, is much fhorter than in the falamander. The 

 lower is articulated with it by a convex furface, fliaped like 

 the fegment of a fphere : its coronoid procefs is very Ihort ; 

 each of its branches is compofed of three pieces at leaft. 

 The teeth are attached to their internal furface, and not im- 

 planted in their edges. The head is articulated to the neck 

 by means of two condyles. 



The bony apparatus of the branchix refembles that of 

 fiflics, with a few llight differences. A longitudinal bony 

 piece bears, at each of its extremities, a pair of tranfverfe 

 portions. Each of thefe anterior portions is joined to a 

 cartilage, which afcends behind the head, fufpended by a 

 ttrong ligament to the fides of the occiput ; it is analogous 

 to the piece which fupports the radii of the branchioilegal 

 membrane in fifties. But here there are no radii ; and there 

 is even a folution of continuity between this piece and the 

 firfl arch of the branchiae. This lirfl: arch, the largeft of 

 all, is joined to the pofterior tranfverfe piece mentioned 

 above. The three others are joined to a third bony piece, 

 fimilar to the preceding, but fufpended behind it, and not 

 articulated to the longitudinal piece. Thefe four arches are 

 fimply cartilaginous. Their fuperior extremity is fufpended 

 to the fecond rib by a ligament, but not articulated to it. 

 Their edges exhibit a feries of fmall fine denticuh, which 

 border the three branchial apertures ; the anterior edge of 

 the fird arch, and the pofterior of the laft, not concurring 

 in the formation of any opening, have none of thele denti- 

 culi. The flvin is immediately attached to thefe arches, and 

 they fupport nothing, as we have already ii ited, analogous 

 to the branchis of fifties. The tufts, which have no bone 

 in their interior, are the only branchix. 



The cfteology of the legs is the fame as iu the lala- 



mander : it comprifes a /lender fcapula, terminated above 

 by a cartilaginous dictation; a large cartilaginous plate, 

 which may be regarded as a double clavicle, analogous to 

 that of the frog, the ufe of which is to proteft the front 

 of the cheft ; a humerus ; two bones of the fore-arm ; a 

 carpus, of which the bones were too fmall and foft to be 

 reckoned ; a metacarpus and phalanges. 



Organs of Seti/e. — The ear is the only one which Cuvicr 

 could obferve accurately ; it feemcd to refemble that of the 

 lalamander. In the outer fide of the bone inclofing the 

 labyrinth, is an oval aperture, fimply clofed by a cartila- 

 ginous plate, covered by foft parts. 



Organs of Circiiktlon anil Rtfpiralion There is a fiiigle 



auricle of confidcrable fize, with its circumference denticu- 

 lated, receiving all the blood of the body, and the lung ; 

 two large valves are placed at the mouth of the vena cava. 

 This auricle communicates with the ventricle by a fingle ori- 

 fice ; and the blood departs from the latter by the aorta 

 only. The heart is therefore exactly the fame as that of 

 the frog, tlie falamander, and of fifties. 



The trunk of the aorta, or rather of the veftel, which 

 in fifties is called the branchial artery, is furniftied with 

 fleftiy and thick fides, and its bafis has three ftrong valves. 

 It divides into three branches on each fide for the three 

 branchial tufts, and no branch goes from it to any other 

 part. Thefe arterial branches become attached to the three 

 cartilaginous arches in their way to the branchia; ; but they 

 form no plexus on them, which proves that branchiae are not 

 attached to thefe arches as in fifties, and as Garden, Ellis, 

 and Camper imagined in the firen. 



Arriving at the branchial tufts, the arteries ramify over 

 all their fubdivifions, and the veins bring back the blood in 

 a contrary dire<5lion. The fame circumftances may be feen 

 in the branchi^ of young aquatic falamanders, in which 

 perhaps the circulation of the blood can be more eafily 

 obferved with the microfcope, than in any other animal 

 organ. 



Having quitted the tufts, the branchial veins afl'ume the 

 texture of arteries, and join togetlier, towards the fpine, to 

 form the defcending aorta ; but they produce, before their 

 union, the branches which in other animals arife from the 

 afcendmg aorta, that is, thole of the head, arms, and lungs : 

 the latter come from the third of thefe branchial veins con- 

 verted into arteries. 



The lungs are two long cylindrical bags, extending to 

 the poft^erior end of the abdomen, and then bent forwards. 

 The veins and arteries form a loofc network on their mem- 

 brane. Air enters them through a larynx placed on the os 

 hyoides, and opening between two fmall rounded margins 

 placed vertically. A very flight cartilaginous prominence 

 is obfervable on each fide in its interior, and the glottis is 

 between thefe : but tliere is no chorda vocalis with a ftiarp 

 edge. Yet it does not follow that the obfervers, who have 

 afcribed a voice to the firen, are inexaft ; for the approxi- 

 mation of the two prominences jult mentioned would be fuf- 

 ficient for its produftion. 



The trachea is a fimple membranous, white, and thick 

 canal, without any perceivable cartilaginous rings. 



Organs of Digeftion. — We have already mentioned the 

 jaws and teeth. The tongue is not fleftiy, nor very move- 

 able : it is fupported, as in fifties, by the anterior extremity 

 of the OS hyoides. It does not refemble that of the fala- 

 mander, and much Icfs that of the frog, both of which are 

 more free behind than in front, and have a very glandular 

 lurface. 



The oefophagus is folded longitudinally. The coats of 

 the ftomac^ ii-e moderately thick ; it firft. fwells a little, 



then 



