CHAPTER XXIV 



REPTILES AND AMPHIBIANS 



GAUDY and motley-colored almost as the brightest birds, butterflies, and 

 fishes, are some of the arboreal lizards and snakes of tropical forests. 

 The lizards are wonderfully light and agile climbers, wanting only wings * to 

 give them full command of the regions of airy outermost foliage, into which 

 they freely penetrate; while the most truly arboreal snakes are scarcely less 

 gifted acrobats, and spend much time in those realms of richest color. With 

 both snakes and lizards, green is the commonest color; but red, yellow, orange, 

 blue, etc., frequently occur on them, in various sharp 'secant,' 'ruptive,' or 

 generalized background-picturing patterns, exactly corresponding to those of 

 the birds inhabiting like regions, though differently modified to suit the lizard's 

 and especially the snake's very different bodily forms. The prevalence of 

 green in their costumes, also, is paralleled among birds, for, as we have seen, 

 the 'lower tier tree-top birds' of the tropics tend to be green; and the strictly 

 arboreal reptiles have almost the same local habitat. 



Both snakes and lizards, and the bright-colored arboreal kinds as well as 

 those of duller tint and humbler situation, are almost without exception obliter- 

 atively shaded, to the full,f and this obliterative shading is almost wholly 

 essential to their concealment. As a snake has the simplest bodily form of 

 all vertebrate creatures, so is his obliterative shading, when complete, the 



* A few kinds (the "dragons,'' Dracho) have even parachute wings, like the flying squirrels. 



t Partial exceptions occur among the burrowing snakes and legless lizards, some of which have 

 almost monochrome surfaces, and among sea snakes. They, however, have obliterative shading in 

 gross, being dark above and light beneath, but with the two shades sharply contrasted instead of 

 connected by intermediate tones. In this they resemble certain whales. Whether or not all the 

 species of sea snake are colored thus crudely, I cannot say. 



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