REPTILES. 



Seba, Thefaurus, torn. i. pi. 104, figs. 3 and 6 ; and 

 Blumenbach's Abbildungen, N" 27. The eyes arc now 

 equidiftant from the end of the fnout, and the poRcrior ex- 

 tremity of the head ; of which the cranium forms nearly one- 

 third. When we look at the adult animal, we'are alloniHicd 

 to find the frontal prominence gone, leaving the head quite 

 flat, and the jaws fo elongated, that the eyes are three times 

 farther from the end of the fnout than from the back of the 

 head ; and the proportion of the face to the cranium is 20 

 inftead of 3 to l. Geoffroy St. Hilaire in the Ann. du Mui". 

 vol. X. p. 77. 



The cameleon exhibits alfo a great difproportion between 

 the cranium and the reft of the head. Its brain, according 

 to the defcription of the Parifian dilTedtors, does not fcem 

 larger than a pea ; and the remainder of the head, which is 

 of confiderable fize, confifts of the large maxillarv bones, the 

 orbits, and immenfe temporal foffae, which, not bt-ing iepa- 

 rated by any partition, give the cranium a very lingular ap- 

 pearance. Defcription Anat. d'un Cameleon, &c. ; or 

 Blafii Anat. Anim. vol. i. p. 14. 



The cranium of frogs and falamanders is almoft prifmatic. 

 The French naturalifts have furnifhed excellent dt fcrip- 

 tions and engravings of the heads of various crocodiles. It 

 will be as well for us to enumerate here the fourecs of in- 

 formation concerning the olleology of this animal altogether, 

 and to give a few references to good figures of the flieletons 

 of other reptiles. 



There are tolerably good reprefentations of the crocodile's 

 ikeleton (the Eait Indian) in Grew's Mufeum Societatis 

 Regiae, and in Faujas St. Fond, Hiftoire de la Montague de 

 St. Pierre de Maellricht, pi. 44. The head of the croco- 

 dile of the Nile (croc, vulgaris, Cuvier), is figured by Geol. 

 froy in the Annalesdu Mufeum, vol. ii. pi. 37, fig. 2. In 

 pi. 4. vol. 10. of the fame work are four figures of the (Icull 

 to illultrate a paper of Geoffroy St. Hilaire, entitled "De- 

 termination des Pieces qui compolent le Crane des Croco- 

 diles ;" and pi. I, of the fame volume, contains nineteen 

 figures of the heads of various crocodiles in different views, 

 to illuflrate Cuvier's paper " Sur les differentcs Efpeces 

 de Crocodiles, vivans & fur lears Carafteres diftinAifs." 

 In the 1 2th volume of the Annals, Cuvier has given his 

 " Obfervations fur I'Ofteelogie des Crocodiles vivans," 

 with two plates, in which moft of the bones are carefully 

 figured. For the Ikeleton of the tupinambis, fee Cuvier, 

 Lemons, v. J. pi. 3 ; of frogs, Roefel, Hifloria Ranarum 

 Noltratium ; of the falamander, Latreille, Hi(t. des Sala- 

 mandres de France ; of the tortoife, falamander, frog, came- 

 letJh, lizard, and a ferpent, Daudin, Hift. Nat. dts Rep- 

 tiles, vol. I ; of the proteus, firen, and Mexican axolotl, 

 Humboldt, Recueil d'Obferv. de Zool. &c. t. i ; of the tor- 

 toife, Blafii Anatomia Animalium ; Cuvier, fur les oli'emens 

 fofliles ; and GeofiVoy St. Hilaire, fur les tortues molles, in 

 the Annales du Mufeum, vol. 14. The fkeleton of the tor- 

 toife is alfo figured in Chefelden's Ofleology ; in Colter's 

 Leftiones Fallopii de Partibus fimilaribus, fol. Norib. 1575 ; 

 and in J. D. Meyer's Zeitvertreib mit Betrachtung curiofer 

 Vorftellungen allerhand Thiere. t. i. tab 29, 31; t. 2. 

 tab. 62 ; and the feparate parts in Caldefi ofTervazioni anato- 

 miche mtorno alle Tartarughe. Firenze, 1687. The flieleton 

 of the common green lizard may be feen in Coitcr, pi. 4 ; 

 in Meyer, t. i. pi. 56 ; that of the falamander and water 

 newt, and of feveral fnakes in Meyer : that of the came- 

 leon is prefixed to Chefelden's 6th ch. Schneider has 

 figured that of the rana pipa in his Hiltor. Amphib. 

 fafcic. I. 



For the form of the head in the different fpecies, a point 

 belonging rather to natural hiftory than comparative ana- 



tomy, we muil refer to the figures already quoted. Tlie 

 furface is more or lets rugous in different fpecimens ; and in 

 many very confiderably fo ; thefe differences are fpecific, 

 only where individuals of the fame age are compared, for the 

 rugofities increafe in fize and i)romineiice in each fpecies with 

 the increa.fe of years. The bony fubllance is often perfo- 

 rated by many fmall holes, as if it were carious or worm- 

 eaten. T!ic futures are conllant ; they are not effaced in 

 the olded heads obferved by Cuvier. 



The Cranium — The cranium of the crocodile, viewed 

 from behind, has the form of a very irregular truncated 

 pyramid ; of which the point or narrowelt portion is down- 

 wards, and the bale excavated to lodge the brain, is up- 

 wards. This pyramid has three furhces, one pofterior, 

 which forms the occiput, and two lateral. The occipital 

 furface is almoft triangular ; one of the angles (the apex 

 of the pyramid) is inferior, tiie other two are fuperior, and 

 greatly prolonged backwards and to the fide, in order to 

 formnhe enormous articular procefies, which receive the 

 lower jaw. Their pofition is 'almoft horizontal. The 

 foramen magnum is fituated in the middle of this furface, 

 and under it the fingle condyle for articulating the head with 

 the vertebral column. 



The futures depart from the foramen magnum, which 

 divide the occiput into particular bones. Tlie fuperior part 

 of the cranyjm is formed by a fingle parietal bone. Ante- 

 rior to it there is an os frontis, alfo fingle, which forms the 

 roof of the orbits. 



The olla teniporum are fituated on each fide of the parie- 

 tal bone, and are partly fupported by that articular procefs 

 for the lower jaw, already mentioned. 



A fmall arch on each fide, different from the zygoma, 

 leaves between it and the parietal bone a large round hole, 

 which perforates the temporal fofl'a. The arch is partly 

 forrned by a procefs of the os temporum, and partly by a 

 particular bone articulated to the junftion of the parietal 

 and frontal. The particular bone occupies the place of the 

 poft-orbitar procefs of the os frontis in the mammalia; for 

 it defcends behind the orbit to join the cheek-bone ; and with 

 it finifhes the frame of the orbits. 



The unufual configuration of the whole head in the cro- 

 codile neceffarily involves very extraordinary modifications 

 of the individual bones, which it is in many cafes exceedingly 

 difficult to refer to their correfponding ones in the crania of 

 the mammalia. For a more minute account of this matter, 

 which could not be eafily underftood without plates, we refer 

 to the memoirs and engravings, already quoted, of Geoffroy 

 and Cuvier. 



A cranium fimilar to this of the crocodile, is found in the 

 other lizards, notwithftanding the great differences in the 

 form, proportion, and the direftion of the parts. In the 

 cameleon, therefore, the foramina, by which the temporal 

 foffa communicate with the cranium, are fo large, and the 

 bony edges which form them fo thin, that the latter repre. 

 fent three flendcr branches rifing to fupport the kind of hel- 

 met vvhicli diftinguifhes this animal. The articular proceffes 

 are not direfted backwards, but downwards. 



The laft pecuharity is alfo obferved in the other lizards, 

 but they have not the crefts of the cameleon, and the upper 

 part of their cranium is broad, like the crocodile. 



In frogs and falamanders the cranium is nearly of a cylin- 

 drical form, flat fuperiorly, and enlarged pofteriorly ; the 

 frontal bones have the fhape of an elongated rectangle, and 

 occupy the interval of the orbits. The Surinam toad has 

 the cranium much flatter than the other genera. 



The eminences intended to afliit in the articulatioa of the 

 jaw are turned direftly towards the fides. 



The 



