941 



GECKOTID^E. 



GECKOTID.E. 



912 



dinal furrow on the internal edge of the jaw by the external surface 

 of their roots. The enamelled crowns are cutting, and their base is 

 rounded. -I'rom their position in the jaw, Wagler has derived his 

 designation Pleurodonts, the teeth being attached laterally while they 

 are free internally, or in the furrow destined for their reception. In 

 the greater number the crown increases from above downwards. 

 These teeth are so closely set that they seem to touch each other, and 

 altogether form a very trenchant dentilated blade, though not long 

 enough for cutting up substances of any thickness, nor does the bite 

 of the animal inflict a wound. 



The oesophagus is very wide, and M. Dume'ril notices an extraordi- 

 nary appearance therein, when it is remembered that the part is not 

 exposed to the light. In many species, both living and dead, which 

 he examined, he found the interior of this canal strongly coloured 

 with different but uniform shades, sometimes of an orange-yellow, 

 but principally of a deep black. There is no distinct limit between 

 the O3sophagus and the stomach ; the crop (jabot) is continuous, and 

 the whole forms a kind of longitudinal sac, which appears to be sud- 

 denly narrowed at the point corresponding to the pylorus, which is 

 not to be detected except by this diminution of diameter and its 

 position on the free and lower edge of the liver. The intestine is 

 arranged in sinuous folds, and about three times the length of the 

 oesophagus and ventriculus taken together, it turns to the left, and is lost 

 on the side of a true and large caecum, furnished with an appendage, 

 and terminating by a large tube which has its opening in the cloaca. 



The triangular liver is placed in the mesial line, but its upper angle 

 is so much elongated, that in some species it forms a conical point, at 

 least twice as long as the base. This point lies in front of the stomach 

 in the space left by the two lungs when they are filled with air. 

 Below, the liver enlarges, and is divided into many lobes or indistinct 

 strips, with the exception of that on the left, which is longest The 

 gall-bladder is situated under the mesial lobe. M. Dume'ril states 

 that there does not appear to be a pancreas, but he observed in the 

 Common Gecko and in the Fimbriated Gecko (Ptyodactyltu fimbriatut) 

 a very small spleen situated on the left side of the stomach. 



Circulating System. The shape of the heart varies. In the 

 Common Gecko it is large and flat, but has nevertheless a tolerably 

 regular conical form, the point of the cone being below, and the 

 base, which is slightly notched, leaning on the root of the two lungs. 

 In the Fimbriated Gecko, on the contrary, M. Dume'ril states the 

 heart to be proportionally smaller, and apparently formed of three 

 distinct but approximated portions, the two upper rounded and oval, 

 resembling auricles, and the other and lower portions small and 

 conical. He acknowledges that he has not followed out the vascular 

 system, but presumes that it resembles in its distribution that of the 

 other Saurians. 



Respiratory System, and Organ of Voice. The glottis consists of 

 a longitudinal slit with two large lips, which form a sort of tubercle 

 behind the posterior notched portion of the tongue, the movements 

 of which it follows, and can consequently be lifted up and applied 

 to the concavity of the palate. The trachea is very large, and the 

 rings, which are cartilaginous anteriorly but membranous on the 

 gide next to the oesophagus, cause it to be considerably flattened. 

 The lungs form two sacs, as in the Salamanders, and are nearly 

 equal in volume and length. Their internal cavity is simple, but 

 there are polygonal cellules on their internal membranous linings, 

 and in the lines forming these the arterial and venous vessels are 

 ramified. The Geckotidce are without any goitre, and M. Dume'ril is 

 unable to account for the production of the voice, but he inquires 

 whether tho cry which they emit, and which is supposed to be in 

 some degree imitated by their names of ' Gecko,' ' Geitje,' &c., may 

 not be assisted by the movements of the tongue, and its reception 

 in the concavity of the palate ; analogous, we suppose, to the pro- 

 duction of the sound with which a coachman or groom stimulates 

 his horses by applying the tongue to the upper part of the mouth 

 and suddenly withdrawing it. 



Urinary and Genital Organs. There is no urinary bladder, nor do 

 the rounded kidneys, whose ureters are not long and open directly 

 into the cloaca, require particular notice. The organs of generation 

 in the males (which are smaller, more agile, and more brightly 

 coloured than the females) are double, and lodged on each side of 

 the base of the tail, which has consequently a swollen appearance. 

 The fggs, which are often deposited between stones, are quite round, 

 with a rather solid, slightly rough, calcareous shell, of a uniform 

 dirty white. M. Dume'ril has seen these eggs produce the young 

 ones, which were well-formed and very nimble. 



The author last named states that he has observed in many species 

 fome peculiar organs, sometimes double, sometimes united in a single 

 flattened elongated mass under the abdominal parietes in front of 

 the pubis, in place of a urinary bladder. They appeared to be of a 

 fatty nature, and were sustained in one part by the os pubis, and on 

 the other possessed vascular or membranous single or double 

 prolongation*, rising in the thickness of the peritoneum as far as the 

 fiver. Though he knows not the office of these organs, he thinks it 

 probable that they may be destined to afford nourishment to the 

 animal in a state of hybernation. The pores of the thighs, &c. secrete 

 a thick humor ; and M. Dume'ril observes that these pores afford no 

 generic character. 



The Oeckolidce are none of them large in size, and the greatest 

 number feed on small animals, such as insects, their larvae and pupse. 

 These they catch either by lying in ambush or by pursuing their 

 feeble prey in the holes and dark crevices to which it retires. The 

 structure of their feet enables them to run in every direction over 

 the smoothest surfaces, and they can even remain suspended beneath 

 the large leaves which a luxuriant tropical vegetation so frequently 

 puts forth. The sharp and retractile nails with which the feet of 

 the greater number are armed, enable them to cling to and make 

 rapid progress on trees with the smoothest bark, to penetrate the 

 holes of rocks, and to climb walls. Of sombre or varying colours 

 adapted generally to the locality where their lot is cast, they will 

 often remain for hours in positions as extraordinary as the flies and 

 insects for which they watch, the wonderful apparatus with which 

 their feet is furnished enabling them to overcome the general law of 

 gravity, and without which they would instantly fall to the earth. 

 The hues of their skins thus render them less objects of suspicion to 

 the little animals for which they lie in wait, and also serve to dodge 

 even the acute eye of the bird of prey that seeks to destroy them. 

 Their eyes, as we have seen, enable them to discern objects in the 

 dark, and are at the same time capable of bearing the rays of a bright 

 sun ; for many insects are nocturnal or crepuscular, while the great 

 mass of them are diurnal. The pursuit of their prey leads them 

 near the habitations of man, whose dwelling always attracts certain 

 kinds of insects, and they sometimes fall victims to their appear- 

 ance, which frequently inspires terror, and often disgust. A Gecko, 

 confident in his powers of flight, appears boldly to await his adver- 

 sary, and his sudden disappearance at a nearer approach adds to the 

 horror which his uncouth form inspires. The poor Geckos too have 

 a bad name. They are supposed to poison whatsoever they touch, 

 be it animate or inanimate, and their saliva is said to vex the skin 

 of those on whom it falls with foul eruptions. Many of these 

 cuticular irritations, when they have actually existed from the interven- 

 tion of these animals, may have arisen from the extremely sharp 

 claws of a Gecko running over a sleeping man, or small blisters 

 may have been raised by the adherent apparatus at the bottom of 

 its feet. 



The Geckotidai are found in all the four quarters of the globe, and 

 are widely distributed in warm climates. In this distribution, Europe, 

 as far as observation has yet gone, claims by far the fewest number. 

 Two species only have yet been found in this quarter of the globe, 

 and even these are common to the northern coasts of Africa. Prince 

 C. L. Bonaparte has noticed them in the ' Fauna Italica,' under the 

 names of Asccdabotei Mauritanicus and Hemidactylus triedrus. The 

 former is a Platydactylw of Dume'ril and others. 



Systematic Arrangement. There can be little doubt that the 

 'AcTKoAajStuTijt of Aristotle and of the Greeks generally was a Gecko. 

 Aristophanes and Theophrastus, as Gesner has shown, speak of those 

 lizards which the Italians called Tarentola, whose bodies were short 

 and thick, and which clambered about the walls in the interior of 

 their edifices for the purpose of catching spiders, on which they fed, 

 under the names of Aicalabotea and Galeotes. That the Stellio of 

 Pliny was no other than a Gecko, Schneider has shown. 



Linnseus placed the Geckos under his great genus Lacerta, and 

 recorded but three species (1766). 



Laurenti (1768) seems to have been the first modern who established 

 the Geckos as a genus. Gmelin (1789, 13th edit, of ' Syst. Nat.') intro- 

 duced a section in the genus Lacerta, consisting of five species, under 

 the name of Gekkones, and the term Gecko was used as a generic 

 appellation for these Saurians by Lacdpede (1790), Schneider (1797), 

 Cuvier (1798), and Brongniart (1801). 



Daudin (1803) divided the genus Gecko into three sections, taking 

 for the basis of his division the number and connection of the toes, 

 the form of the tail, and the disposition of the scales. These sections 

 consisted of the Geckos properly so called, the Geckottes, and the 

 Geckos with a flat tail. M. Dume'ril, who has written so much and 

 so well on this subject, and to whose writings we are so much indebted, 

 states that in 1806 he profited by the foregoing works, and established 

 in the 'Zoologie Analytique," and in his public lectures the genus 

 Uroplatus (1806), and he says that Oppel, in his 'Prodromus' (1811), 

 established the family Geckotidai after his (Dumdril's) indications. 

 M. Dume'ril, who established also the genus Urotornus, adopts in great 

 measure the system of Cuvier, and separates the Geckotidai into two 

 great divisions, each embracing subdivisions. These divisions take 

 the structure of the toes for their basis ; the first consisting of those 

 Geckotidce which have dilated toes, the second of those whose toes are 

 not dilated. The subdivisions depend upon the variation in the 

 structure of the lower pari of the toes. The genera are Ascalaboten, 

 Platydactylua, Hemidactylus, Ptyodactylus, Thecadactylus, Sleno- 

 dactylus, and Gymnodactylua (1836). 



Cuvier (1817-1829) placed these Saurians under his great genus 

 Gecko, which he divided into the following sub-genera : Platydactylus, 

 Hemidactylm, Thecadactylus, Ptyodactylus, Sphceriodactylus ; at the 

 same time arranging those Geckos which have retractile claws, but 

 slender or rather not enlarged toes, in three groups, under the names 

 of Stenodactylui, Gymnodactylus, and Phyllura, the latter embracing 

 those with a horizontally-flattened foliated tail. 



Merrem (1820) places the Geckos in the first tribe (Gradientia) of 



