obliteration by means of background pictures. There are many other types of 

 ground-picturing pattern, more or less elaborately developed, among terrestrial 

 sedentary snakes. That of the loathsome and beautiful African Puff Adder 

 (Clotho arietans) is a good example of the desert type, which numbers many 

 species, both of snakes and lizards. The Puff Adder, and all of his kindred 

 which bear equally minute sand-pictures, are to the highest imaginable degree 

 fitted for "lying close" — more so, perhaps, even than such a wonder as the 

 Copperhead. Lizards' picture-patterns do not often reach quite such minute 

 finish, and this is in keeping with the fact that almost all lizards are quick and 

 agile. Most kinds, though they may "lie close," are yet always ready to resort 

 to sudden and swift dashes in case of pressing danger ; and they often catch their 

 prey by long leaps or even running chases. The picture-patterns of lizards ac- 

 cordingly tend to be more generalized and crude than those of snakes, but there 

 are of course many exceptions on both sides. Some tree-bark patterns of 

 arboreal lizards, for instance, are perhaps as highly specialized as any snakes' 

 patterns. (See Fig. 124.) Lizards, furthermore, have in many cases the won- 

 derful power of sudden color-change, or 'chameleonism,' which is, I believe, 

 wholly wanting among snakes. This phenomenon, mentioned in the last chap- 

 ter, is too well known to need detailed comment here. Suffice it to say that the 

 various adaptive costumes which the lizards assume and doff are practically all 

 and always equipped with full obliterative shading, and often with highly- 

 wrought background-pictures. (See Appendix A.) 



One more type of marking among snakes calls for especial mention. That 

 is the sylvan sun-and-shadow or 'leaf-checker '* pattern worn by some of the 

 big tree-boas and pythons. This type of pattern and its uses have already 

 been described at some length in Chapter XXI, in connection with leopards, 

 giraffes, etc. On snakes its form is somewhat different, as the reader will see 

 by an examination of the bits of boa pattern shown in Fig. 120, but the general 

 effect is much the same. Indeed, the resemblance in pattern between some of 

 these bits of boa and some of ocelot (Fig. 120), is close. 



* (and hole-picturing)— A. II. T. 



m 



