OECKOTIDjE. 



GECKOTIh K. 



Muscular SytUrn. The m uncles of the GtdMida are highly irritable, 

 u might be expected in Mioh nimble creature*. Their power of 

 adhering to unooth surfaces make* it necessary that the reautanoe 

 produced by the adhesion should bo instantaneously overcome in cue of 

 danger; and we accordingly find that a Gecko which at one moment 

 U fixed motionleM to a spot, vanishes u it were in the next from 

 under the hand stretched forth to capture it 



The brain and nervous system are considerably developed in the 

 OtctotiJa, and the greater part of the senses are acute. 



Sight The orbits, as we have seen, are large and without any 

 flooring or base, and as the eye in this family is very large in propor- 

 tion to the size of the animal, the projection of the posterior part of 

 the globe may be seen in the inside of the mouth much in the same 

 way as is observable in some fishes. There is scarcely any lid, and 

 what there is is so small that an additional appearance of prominence 

 U given to the eyebalL This lid is simple, circular, and adherent to 

 the globe of the eye by an internal fold. There U a nictitating mem- 

 brane. Most persons have seen that an epidermic scale which seems 

 to be the external layer of the cornea comes off in serpents with the 

 rest of the skin, and in the Geckos also the integument passes over 

 the front of the eyeball. The eye in such animals never appears 

 humid. M. Jules Cloquet has shown that in the serpents the tears 

 probably are diffused between the epidermic scale and cornea in order 

 to arrive at the nostrils. The pupil is sometimes rounded, but most 

 frequently presents a linear slit, the edges of which are fringed, so 

 that the animal can at its pleasure dilate or diminish the opening 

 through which the light and the images are to be admitted to the 

 retina. Like the Cats therefore, the Geckos, though said to be 

 nocturnal in their habits, can also see perfectly well in broad daylight 



Hearing. The auditory apertures in this family are sometimes in 

 the form of slits, sometimes in that of oval or circular holes, and the 

 edges are often rounded and sometimes dentilated. Wagler states 

 that these apertures can be closed in Ptyodactyliu &nd Spheriodactyltu, 

 and it is extremely probable that the rims have a power of approxi- 

 mation generally. The tympanum lies deep, and the auditory cavity 

 communicates with the back of the mouth or throat for the admission 

 of air, as in most pulmoniferous animals. H. Dume'ril says, that he 

 has proved the sensibility of these nim>l to the least noises, and 

 that their sense of hearing is very fine. 



Smell The structure of the nostrils in this family would not 

 lead to the conclusion that their sense of smelling is very acute, 

 though it is probably more highly developed than it is in the Frogs. 



Taste. The Oeckolidce swallow their prey living, or nearly so, and 

 almost entire, but the presence and form of the teeth render it pro- 

 bable that they can masticate ; and this power, combined as it is with 

 the form and structure of the tongue, which is soft, moveable, very 

 fleshy, and furnished with papilla:, seems to indicate a certain degree 

 of the sense of taste. 



Touch and Integuments. The skin of the Geckos is generally 

 delicate, and adheres but little to the muscles, from which it in easily 

 detached. In the middle of the back, and sometimes on the sides, 

 granular tubercles rounded on their edges, with others which project 

 at the centre, and are even fashioned into facets, are to be detected in 

 the greater number. When the skin is detached and held up to the 

 light it is seen to be regularly furnished with small delicate rounded 

 escutcheon-like bodies, set in the thickness of the skin. The form aud 

 distribution of these bodies vary according to the different species in 

 the regions of the belly, of the neck, of the thighs, of the head, and of 

 the tail. M. DumeVil, who gives us this information, goes on to state 

 that generally the skin of the Gedcolidte is gray or yellowish, but that 

 there are species in which lively colours are disposed on some parts 

 of their bodies, and that it is even said that tiuts of red, blue, aud 

 yellow may be distinguished, which the animal causes to appear and 

 disappear nearly after the manner of the chameleons. Some travellers 

 assured Wagler that certain Indian Geckos became luminous or 

 phosphorescent during the night 



In some of the species the skin is prolonged on the sides of the 

 body and tail into membranes regularly festooned or fringed, and the 

 Geckos generally moult or change their skins at certain periods of the 

 year, when their colours, as is usual in such cases, become brighter. 

 M. Dumeril says that be has himself observed this in living individuals 

 captured in their wild state at Cordova, in Spain, in the middle of the 

 summer. There can be little doubt that there is considerable sensi- 

 bility where the akin is constructed as it is in the Geckos ; but in 

 considering the sense of touch, the curious organisation of the feet 

 and toes demands our particular attention. These are the great organs 

 of station or fixation and progression, and the manner in which they 

 perform their office is very interesting. H. Dunu-ril, after referring 

 to Wagler's reflections on this subject in his remarks on the J'laiy- 

 glotii, gives his own observations on this part of the organisation of 

 the Geckos. He refers to the comparative shortness and general 

 structure of the feet above given, and then proceeds to notice the 

 particular conformation of the toes in the greatest number of species. 

 The lower surface of these, and the sole, are very much dilated, 

 widened, and furnished with small plate* or lamella!, following or 

 overlying each other (lamelles placee* en recouvrement) in a regular 

 manner, but in a mode which vane* in the different species. The 

 which are sometimes wanting on all the toes, are most 



frequently pointed, hooked, and more or less retractile, constituting a 

 sort of claws, which remain constantly sharp. The toes are some- 

 times united at their base, and, as it were, semipalmatod. In some of 

 the species, Ptywlactyltu and Spkeriodactyliu of Cuvier, for instance, 

 the extremity of the toe* expands, and widens considerably in form of 

 a fan or semi-disc, as in the Tree- Frogs. 



The membranous and soft plates with which the lower surface of 

 the toes of the Geckos are furnished present a variety of modifications 

 in the different genera. Sometimes they are simple, or continued 

 from one edge to the other, and those of this class offer distinctions in 

 the furrows themselves, and in the curves described by the lines 

 which mark them ; sometimes they are separated longitudinally by a 

 groove ; sometimes they are complete or continued throughout the 

 length ; sometimes they exist on the last phalanges only ; and lastly, 

 in the aberrant genera they are hardly distinct The modifications of 

 this curious apparatus, as well as the absence or presence of the nails, 

 afford the leading characters on which herpetologists have esta- 

 blished the different genera, and we here present the various forms 

 collected by M. Dumc'ril. 



Is 



Form and structure of the under part of the toes of Geckotidte. The figure 

 marked with the numeral only, represents the foot : the figure marked with the 

 added letter a, represents the structure of the lower part of the toe. 2, 1'laty- 

 dactylus Cfprdtatita ; 3, Platydnctyht* .ftgi/ptiocul ; 4, 1'latydartylu* giittntui 

 <;rck<> rfriia, Common Gecko, of Gray); 5, Platydactylus homaloccphtilu* 

 (Ptychosoon, of Kiihl; fltropleura, of Gray); C, Plalydadylui Ltathianut 

 (Alralabo/fi Isachianui ; Grift*., ' Anim. King.') ; 7, llemidaclylut Oualaisit 

 (Ptrofui, of Wiegmana) ; 8, lltmidactyltu tricdrut. 



The numerals and letters Indicate the same parts at they do In the upper 

 fiiture, with the exception of 7, i, which represents a claw in profile. 2, Therii- 

 inctylui Tkteonyx ; 3, Ptyodaclylut llauelquutii (P. futtatiu, of KUppell, 

 House-Oecko, Griff. ' Anim. King.') ; 4, Ptyodactylui fimMattu (llreko 

 fimbriatiu of authors ; Fimbriated Gecko, Griff., ' Anim. King.') ; 5, 1'kyllo. 

 ilaclylia porphyreui ; 6, Gymnoditctytiu tealitr (Stmoilailylui icaber of 

 Rilppcll ; Cyrtodactylttt, of Gray I) , 7, Gymnodaclytut pulchtllta (Oonyodac- 

 tylia futchtllui of Wagler ; Oyrlodactylut pulchellut, of Gray) ; 7, t represents 

 s claw of the animal seen In profile. 



Digestive System. The numerous teeth of the Geckoa are similar 

 in form and length, placed on the same line, and fixed in a longitu- 



