unnoticed. This is true especially of transverse marks. Lengthwise marks, as 

 has been explained in an earlier chapter, are much less conspicuous on a moving 

 object than those in any degree transverse. Stripes running the whole length 

 of the body, such as are worn by certain snakes, add nothing to the conspicuous- 

 ness of motion,* and in fact tend to lessen it, inasmuch as they split their 

 wearers' forms, so to speak, into narrow, parallel lines of different colors or 

 shades, some of which are likely to match the moving reptiles' backgrounds. 

 Markings of this kind also, are, I believe, almost wholly confined to swift hunt- 

 ing-snakes. On the other hand, although some snakes by no means sluggish 

 are transversely ringed (e. g., some of the coral snakes), yet markings of this type 

 characteristically belong to species which spend most of their time at rest, and 

 often or habitually lie in wait for their prey. Such markings, indeed, are as 

 particularly well fitted to conceal a motionless snake as they are ill fitted to lessen 

 the conspicuousness of one in motion. For, aided by background-marks of like 

 aspect and direction, they ' cut up ' the motionless snake's long form into short, 

 un-snake-like segments. Lengthwise stripes, under the same conditions, have 

 merely the effect of ' splitting' their wearer's form into several narrow but snake- 

 like parts. So also many of the lizards that persistently "lie close" have bold, 

 transversely 'secant' bands. Such are most of the iguanas, and a great many 

 smaller species, both arboreal and terrestrial. Even the ' oilcloth '-plaided 

 pattern of the sluggish Gila Monster (Helodermata) is transverse rather than 

 longitudinal. More or less transverse also, though minutely varied and elabo- 

 rated, are the beautiful and terribly effective ground-picturing patterns of 

 such sedentary poisonous snakes as the Rattlers and the Copperhead (Cro- 

 talus and Trigonocephalies). (See Fig. 123.) The Copperhead's pattern is 

 especially remarkable. As the reader will see by looking at Plate XI, it pic- 

 tures with astounding accuracy heaped dead leaves, with their lights and 

 shadows. This wonderful resemblance, like the rest, owes its power primarily 

 to the underlying or inwoven counter gradation of shades, whereby the snake's 

 cylindrical solid form is visually 'flattened out,' and prepared for complete 



* (i. e., of longitudinal motion) — A. H. T. 

 174 



