REPTILES. 



although the teetli, as in all other cafes, are formed by fuc- 

 ceflive ilrata. 



" The capfule containing the new tootii is not cncloftd 

 in a feparatc cell of the maxillary bone, as in the mammalia, 

 but it lies in the bottom of the fockct of the tooth which 

 it is defigned to fucceed. This little (lic-U is tirft (5n the 

 internal fiirface of the root of the tooth in place ; it occa- 

 fions a groove in this part, by which, as it increa-fes in 

 length, it penetrate? into the hollow of the latter, and then 

 deftroys by its prelTure the pulp that filled its cavity, and 

 furniihed the materials of its increafe. Hen:e, at what- 

 ever age we may remove a crocodile's teeth, we Ihall find, 

 either in the alveolus, or in the cavity of the tooth itfelf, a 

 fmall tooth, either in the form of a thin and fliort (hell, or 

 more advanced and ready to occupy its place, when the 

 old and enveloping tooth fiiall have been difcharged. This 

 fuccefiion loems to be repeated as long as the animal lives : 

 hence the teeth always appear (liarp and frefli, and although 

 larger, they are not much more worn in old than in young 

 crocodiles. I have alcertained all thefe fatls in a recer.t 

 head, and in others preferved in fpirits of wine : and I 

 could didinguiili very clearly pulps and capfules fimilar to 

 tliofe of quadrupeds. 



" Tliis procefs was tolerably well underftood by Per- 

 ranlt and Duvcrney ; Mem. pour fervir a I'Hiftoirc des 

 Animaux, v. iii. p. 167. 



"As the teeth of the crocodiles are generally nearly 

 perfeft cones, and enlarge to their very bafis, how can 

 they come out of the alveoli, of which the entrance is 

 much narrower than their bafe ? The new tooth, as it is 

 developed and fills the cavity of the old, comprefles its 

 fubftance againlt the focket, deftroys its confidence, makes 

 it crack, and thus difpofes it to be feparated on the flighteft 

 ftiock at the level of the gum. The fragments are eafily 

 thruft out of the fockets. We often find in the fockets of 

 crocodiles, when changing their teeth, rings formed by the 

 relics of the old teeth left behind, through which the new 

 are making their w.iy : and fuch are alfo found in the fofiil 

 jaws of true crocodiles. 



" The bafe of the cone is generally not entire, but 

 exhibits a more or lefs deep fiil'ure on its internal fide : it 

 has been already mentioned that this is caufed by the pref- 

 fure of the germ of the new tooth. Wiiile the germ is 

 very imall, this fiffure does not exift, and the germ itfelf 

 never exhibits it. 



" Although the teeth may be faid to be all alike, and 

 arranged in an uniform feries, fome are rather larger than 

 the reft ; and the greater this inequality, the more irre- 

 gular is the line of the jaws. 



" Thefe larger teeth are either received into grooves of 

 the oppofite jaw, or into holes, or they perforate it com- 

 pletely. 



" In the caimans or alligators, the firft: of Cuvier's 

 fubgenera, (containing the American fpecies,) there are 

 from nineteen to twenty-two teeth on each fide below, and 

 nineteen or twenty above. The two firit of the lower 

 jaw penetrate at a certain age the front of the upper jaw, 

 and go completely through it. The foin-th of the fame jaw 

 are the longeft, and go into the holes of the upper jaw, 

 in which they are entirely concealed v>'hen the mouth is 

 (hut. The five front in the upper jaw are intermaxillary 

 teeth. 



" The firft; and fourth of the lower jaw are long in all 

 the three fubgenera ; next to thefe come the eighth and 

 ninth of the upper, the eleventli of the lower jav,' in the 

 true crocodiles and caimans. The caiman with bony eye-lids 

 (crocodilus palpebrofus) has the twelfth below and the tenth 



Vol. XXIX. 



above the longeft. After the fourth in the gavials (Ion. 

 giroftres) they are all nearly equal, fo that the jaws in 

 thefe have not fo waving a line as in the other fub- 

 genera. 



" The fourth tooth below might be called canine, from its 

 fupcrior length, and bccanfe it correfponds to the future 

 between the maxillary and intermaxillary portion of the 

 upper jaw. 



" In the fecond fub-gcnus, or proper crocodiles, there 

 arc fifteen teeth on each fide below, and nineteen above. 

 The firft of the lower jaw penetrate the upper; the fourth 

 pafs into grooves, and arc not lodged in cavities of the 

 upper jaw. 



" The gavials (longiroftres) have 25—27 on each fide 

 below, and 27 — 28 above. The two firft and the two 

 fourth of the lower pafs into grooves, not into perforations 

 or cavities of the upper." 



In the tupinambis ot the Nile we find fixteen above, of 

 which five are intermaxillary, thirteen below ; all conical, 

 and nightly bent backwards : the pofterior are the largell 

 and moft obtufe. In a tupinambis from the Moluccas 

 there were fix above, and feven below, all comprefled and 

 pointed. 



The teeth of the common lizard, the iguana, and agame, 

 are cutting, and more or lefs fcrrated on the edges ; they 

 are all fo in the iguana, where feveral have fix or eight 

 denticulations, and there are twenty or twenty-one teetti on 

 each fide. The common hzard has twenty-one or twenty- 

 two, but the anterior are not fenfibly denticulated, and the 

 others have merely a groove. The agame has nineteen or 

 twenty, all with three denticulations. In thefe three genera 

 they increale in fize from before backwards. 



They are triangular, with a little groove before and 

 behind, in the ftelHo : there are fixteen or feventeen fuoh 

 on each fide, and two large conical canine teeth. There 

 are, moreover, two fmall conical intermaxillary teeth above, 

 to which nothing correfponds beloAV. 



The dragon correfponds to the ftellio in its teeth, except 

 that the canine are proportionally longer than the incifors : 

 the number is the fame. There is a good reprefentation of 

 them in Blumenbacli, Abbildungen Natur-Hiftorifcher ge- 

 genftande. No. 98. 



The gecko has thirty-five or thirty-fix teeth on each fide, 

 all of equal fize, clofe, fimple, flender, and pointed. The 

 flat-headed gecko has feventy or feventy-four on each 

 fide. There are twenty-two on each fide, above and below, 

 in the fcink, all conical, ftiort, clofely fet, and of equal 

 fize. 



The cameleon has, on each fide, eighteen above and nine- 

 teen below ; of which the anterior are very fine, the pofte- 

 rior much larger, and furniftied with three points. 



Teeth of the Batracians All thefe have teeth in the 



palate ; as to the jaws, the falamanders have them in 

 both, the frogs in the fuperior only, and the toads in 

 neither. 



The palatine teeth form, in the toads and frogs, a tranf- 

 verfe line, interrupted in the middle. They are implanted 

 in the palate bones. They form two lang parallel lines in 

 the falamander. 



The maxillary teeth are fmall, pointed, and clofely fet. 

 The frog has about forty on each fide above, eight of 

 which are intermaxillary ; the falamander fixty, both above 

 and below, and thirty on each fide of the palate. 



Teeth of the Ophid'mns. — The ferpents are di\-ided firft into 



two families, thofe which can, and thofe which cannot, 



feparate the two halves of the upper jaw. The former 



have no incifor teeth ; but they have palatine, maxdlary, and 



4 X mandibular. 



