273 REPTILIA. 



A second subdivision is formed of (lie Ilou'/dnrfj/Ir.s, \vlii.;h liMve an oval disl-; at the base of their toes, formed 

 by a double ranixe of chevron scales iindei-neath ; the middle of tliis disk elevates the second phalanx, ^vliich is 

 slender, and bears the third, witli its claw, at the extremity. The known species have all live claws, and the range 

 of pores on either side of the anus ; the scales underneath the tail form bi-oad bands, as in the true Serpents. 



A third subdivision, which I style T/wcadacfi/lct,; have toes widened throughout their length, and furnished 

 "with transverse scales underneatli, bat which latter are divided by a deep longitudinal groove, into ^^hich the 

 claw retracts completely. 'I'liose known to me havi; tiie tliunib alone clawless, no femoral pores, and the tail 

 covered with little scales both above aiid bijlow. 



The fourth subdivision of Geckos, 1 term P/i/odach/Ics. These have only the ends of their toes dilated into 

 plates, with a fan-like structure beneath ; the middle of the plate being split, and the claw placed in its fissure. 

 They have very crooked claws on all their toes. 



Some liave a round tail, and five toes ; while othei's liave the tail bordered Avith a memlirane on each &ide, and 

 the toes palmated. It is probable that the latter are acjuatic, and they are the Urop/ates of Dumeril. 



A fifth subdivision is composed of the SpI/cfiodacfj/Ies, — which are certain small Geckos, the end.s of the tor-s of 

 which are terminated by a little palette without folds, but the claws of which are always retractile. Tln-se in which 

 the palette is double, or emarginated in front, approximate the round-tailed Ptyodactyles. ]\Iore freijuently, )iO"\v- 

 ever, the palette is round and simple. All the known species are from India and the Cape. 



Finallv, there are certain of these Saurians which, with all the other characters of the Geckos, have the toes not 

 widened. Their claws, five in nunjber, are nevertheless reti-actile. Some of these, with a round tail, and the toes 

 striated beneath, having dentelated edges, constitute the •Sfenodncfi/Zcs ;^ani\ thei'e are others with :>lender and 

 naked toes, and also a round tad, which are the Gi/miiodacfi/les of Spix. 



Some, again, have the tail horizontally fiattened, in the form of a leaf, which 1 denomniate Phitlitnis. 



One species only is as yet known, from New Holland. 



TIIE FIFTH FAMILY OF TIIE SAURIANS,— 



The Chameleons {Cha'in(slco,h\\\.),— 

 Arc so very distinct from the otlier Saurians that it is not easy to intercalate them in the series. 



All have tliC skin roughened with little scaly granules ; the body compressed, and the dorsal line 

 sharp ; tail round and prehensile ; five toes on each foot, but divided into two opposite sets, one con- 

 sisting of two toes, and the other of llie remainder, — the toes of eacli of these sets being connected bv 

 skin as far as the nads ; tlie tongue is tlc^by, cylindrical, and extremely protrusile ; the teeth trilo- 

 bate; the eyes large, l)ut almost covered by the skin, which leaves only a little aperture opposite the 

 pupil, and they are moveable independently one of the otlier; llie ear not visible externally, and the 

 occiput pyramidicaUy raised. Their first riljs are joined to the sternum, and the remainder are each 

 continued to join the corresponding rib of the other side, encircling tlie alidomen by complete hoops. 

 The lung is so vast that, when inflated, tlie body appears transparent, ami induced the ancients to 

 beheve that these animals fed upon air. They subsist on insects, whicli they take with the glutinous 

 extremity of the tongue, which organ is the only part of them that moves quickly. The motion of the 

 limlis is excessively slow. The magnitude of the lung is probably the indirect cause of their changing 

 colour, which does not take place, as is currently supposed, for the purpose of assimilating them to the 

 proximate surfaces, but according to tlieir wants and jiassions. Their lung, in fact, renders ihera more 

 or less transparent, liy forcing tlic hluod more or less into the vessels uf the skin, the colour even of 

 this fluid being mere or less vivid according as the lung is distended with air. They are constantly 

 found upon trees. 



[These most singular animals are iiartimlarly rcmarkal^le fnr the diniinislied sympathy of tlie two sides of their 

 whole frame, one of which may be asleep and the other awake, one of one colour anil the other of anoth^.i-, &c., — 

 the separate movement of their eyes being merely another phase of the same phenomenon : hence it is remarkable, 

 that, unlike most other animals, the Chameleon is totally unable to swim, from the incapability of its Umbs 

 of acting ui due concert.] 



THE SIXTH FAMILY OF TIIE SAURIANS,— 

 The Scin doioiens, — 



Arc recognized by t!ic shortness of their feet, the non-extensibility of the tongue, and the c)[uality of 

 the tile-hkc scales wliieh cover the whole ))oily and tail. 



TiiK SciNC-ir^s {Sciiicns, Daud.) — 

 Have four very short feet, a bndy of nearly the same calibre with the tail, no occipital bulge, no crest 

 or throat aiipendage, and the si-alcs uniform and shining, anrl disposed tile-fashion like those uf a Cari). 



