538 



Observations on a few Species of Gechos, 



[No. 5, 



black color and a brilliant light emerald green, but this change is not 

 more remarkable than that which takes place in the more humbly 

 coloured species ; for in many, not only the general colour changes but 

 brilliant markings suddenly appear, which were previously invisible, 

 f An animal which is of a dull grey and transparent, and without any 

 apparent markings, when examined in one of my boxes and held up 

 to a strong light, may, when placed in a more subdued light, assume a 

 brilliant tortoise shell hue, or a light straw, or perhaps become nearly 

 black : such extremes and differences in colour are truly surprising. 



Most Geckos have five distinct toes. The thumb is more or less 

 defined, and the toes are furnished with or are without sucking pads 

 possessing more or less adhesive powers ; those which have the pads 

 less developed, or confined to the tips of their toes, find greater 

 difficulty in ascending plane vertical surfaces than those which have 

 the suckers fully developed. In some of the small species which 

 frequent walls, a membrane unites the toes ; while others possess 

 membranes on the sides of their tails, heads and bodies ; according to 

 which characters the group is separated into several genera. A 

 peculiarity in the claw of the gecko is its powerful retractility, 

 which in some species is not confined to the claw, but is in a great 

 measure possessed by the entire toe : the sucking pad is even capable 

 of reduction, either by a folding process or an internal retraction. 

 Another strange peculiarity is in the eye, which is furnished 

 with a transparent case, behind which, the eye moves freely and 

 rapidly. 



In casting their skins, the portion over the face draws off from the 

 nose towards the occiput, leaving the case of the eye, in some, un- 

 changed. This, it will be perceived, is different from the process which 

 obtains in the case of a snake when casting its skin, for in the latter case, 

 the case over the eye is invariably renewed with the skin. I have already 

 alluded to Geckos being entirely insect-eaters, and they are active insect- 

 destroyers ; but for all that, they are remarkably choice in the selection 

 of their prey, as they may be seen for a considerable length of time, 

 perfectly motionless on a wall, watching some particular insect they 

 may have selected for their food ; and they will, in the meantime, allow 

 numbers of others to pass their very mouths, without making the 

 slightest effort to secure them. Flies and cockroaches form a very 

 favourite food, but the insect must be alive, or they will not touch it. 



