Chap. IV. IN ANIMALS. 105 



Chameleons and some other lizards inflate themselves 

 when angry. Tims a species inhabiting Oregon, the 

 Tapaya Donglasu, is slow in its movements and does 

 not bite, but has a ferocious aspect; " when irritated 

 it springs in a most threatening manner at anything 

 pointed at it, at the same time opening its mouth wide 

 and hissing audibly, after which it inflates its body, and 

 shows other marks of anger." 22 



Several kinds of snakes likewise inflate themselves 

 when irritated. The puff-adder (Clotlio arietans) is re- 

 markable in this respect; but I believe, after carefully 

 watching these animals, that they do not act thus for 

 the sake of increasing their apparent bulk, but simply 

 for inhaling a large supply of air, so as to produce their 

 surprisingly loud, harsh, and prolonged hissing sound. 

 The Cobras-de-capello, when irritated, enlarge them- 

 selves a little, and hiss moderately; but, at the same 

 time thev lift their heads aloft, and dilate bv means of 

 their elongated anterior ribs, the skin on each side of 

 the neck into a large flat disk, — the so-called hood. "With 

 their widely opened mouths, they then assume a terrific 

 aspect. The benefit thus derived ought to be consider- 

 able, in order to compensate for the somewhat lessened 

 rapidity (though this is still great) with which, when di- 

 lated, they can strike at their enemies or prey; on the 

 same principle that a broad, thin piece of wood cannot 

 be moved through the air so quickly as a small round 

 stick. An innocuous snake, the Tropidonotus macroph- 

 thahnus, an inhabitant of India, likewise dilates its neck 

 when irritated; and consequently is often mistaken for 

 its compatriot, the deadly Cobra. 23 This resemblance 

 perhaps serves as some protection to the Tropidonotus. 



22 See the account of the habits of this animal by Dr. 

 Cooper, as quoted in ' Nature,' April 27, 1871, p. 512. 



23 Dr. Giinther, ' Eeptiles of British India,' p. 262. 



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