980 ZOOLOGY. 
skin to the subjacent muscles,—a feature highly conspicuous in the chame- 
leon. The skin appears to be provided with various coloring matters, in 
different layers, which may be exhibited at or near the surface, under 
different circumstances and to different degrees, thus producing the various 
shades of color. These colors depend much upon external conditions, but 
are especially seen when the animal is irritated, or exposed to an elevated tem- 
perature. When remaining in a dark, cool place, the color of the skin is 
~ nearly white, which the stimulus of light and heat soon converts into a bottle- 
green, or venous red, this sometimes of such intensity as to appear almost 
black. These colors may be partial in their distribution, or may cover the 
whole body. 
_ The family is represented by a single genus, Chameleo (pl. 74, fig. 72), 
which is confined entirely to the Old World. Most of the species are 
African. One species, C. vulgaris (pl. 88, fig. 3), is found in the South of 
Kurope. 
Fam. 6. Geckonide. The Gecko family is eminently nocturnal, the 
entire organization fitting the species for this life. With some resem- 
blance to the last, in some parts, the geckos are characterized in the first 
place by a clumsy, depressed body, so low on the legs as to permit the 
abdomen to drag along the ground; the greatest thickness is in the middle, 
and the back is without crest. The feet are short; the toes usually 
dilated, and provided beneath with transverse folds of skin, by means of 
which they are enabled to adhere firmly to the surface over which they 
may be moving. The claws are sharp, curved, and in some species re- 
tractile. The head is large and depressed, the mouth extensive, the eyes 
very large and protruding. In most species the pupil is a vertical slit, 
with or without denticulated margins. The tongue is short, fleshy, not 
protractile, and free at the extremity. The teeth are small, uniform, and 
implanted along the inner margin of the jaws. The tail is frequently 
provided with curious appendages, never, however, with a dorsal crest. 
The skin is granulated, somewhat as in the Chameleons. In some 
species, it is extended along the sides and limbs into a kind of marginal 
fringe. | | 
The Geckonide, unlike the last family, are pretty generally distributed. 
Asia, Africa, America, and Australia, divide the species pretty equally. 
Europe possesses two species. None are found in the United States, a 
species of Platydactylus having been assigned erroneously. The entire 
family may, with Cuvier, be conveniently divided into seven sections, 
according to the structure of the toes. In the first section, Platydactyla, 
the toes are more or less enlarged along their entire length, and provided be- 
neath with transverse imbricated laminz, which are either entire or divided by 
a longitudinal median furrow. A species of Gecko, Platydactylus muralis, 
is common in Southern Europe, where it excites attention by its power of as- 
cending smooth perpendicular walls. It is this species which is called Taran- 
tola or Tarantula, by the Italians. Another species, P. guttatus (pl. 88, 
jig. 4), is a native of Asia. 
_ The second section, Hemidactyla, embraces species in which the toes 
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