3 68 



NATURE 



\August i j, 1882 



There is, therefore, no fear of the new Reptile House 

 lacking inhabitants, when ready to receive them next 

 year. 



DIFFICULT CASES OF MIMICRY 



I SEE a notice regarding mimicry and simulation, by 

 Mr. A. R. Wallace, in Nature, vol. xxvi. p. 86, and 

 beg to forward the case of a caterpillar mimicking a shrew, 

 as a peculiar instance of this curious law. 



Here we see the insect unconsciously simulating the 

 very animal that most likely feels on itself, or at least an 

 insectivorous minimal. Passing through a dense forest 

 near a path, I suddenly came on the caterpillar, at about 

 five feet fro.n the ground, on a stout creeper, and of course 

 mistook it for a shrew. Its remaining, and not running 

 off, induced me to look closer, when I saw the green 



markings, and at once secured the prize, and, after 

 making a sketch or two, put it in my " hatching " cage ; 

 unfortunately, I could not find what it fed on, and after 

 spinning a pale greenish cocoon, it died. The natives did 

 not seem to know it. When moving along, it does so as 

 other caterpillars, as seen in the outline 1, of which 2 is 

 plan of the head. If suddenly disturbed, it at once strikes 

 the peculiar pose, as seen in the' sketches, and retains it 

 for some time. 



The general colour is a neutral to brown-grey, beauti- 

 fully marked, and which I have not attempted to imitate ; 

 the general appearance is dark, except where the greenish- 

 yellow spots occur. It is the first case I know where a 

 caterpillar mimics a vertebrate animal. The cases are 

 almost innumerable out here, where insects mimic each 

 other and similar or different kinds, or leaves, seeds, 

 flowers, sticks, pieces of grass or clay, &c, &c. ; but we 



see it also in many other cases, not always protective, 

 though invaluable to the animal or the insect. The tiger 

 has one call, when hunting, so like the loud whistle of the 

 Sambsr (deer) that only an expert and old resident can 

 tell the difference. The deer, if within range, run to it, 

 and I have myself shot a Samber at twenty yards that 

 dashed up on my whistling loudly, with a leaf; unfor- 

 tunately, native shikaries are only too expert at this. 

 Again, the eye and nose lumps of a crocodile are so like 

 lumps of foam that I have often drifted past close to one 

 in my Rob Roy, and only found it out by the lump of 

 foam quietly and suddenly sinking below the surface of 

 the muddy water. In the case of the tiger the simulation 

 was by sound, to enable it to get food ; in that of the 

 crocodile the same end is gained by simulation of 

 appearance, enabling the animal to drift close to prey 

 without alarming it. S. E. Peal 



Asam, June 25 



THE WASHBURN\ CHRONOGRAPH 



THE article on the Brussels Chronograph (Nature, 

 vol. xxvi. p. 107) induces me to send a brief de- 

 s:ription of the chronograph of this observatory, which 

 miy be taken as representing the form usually adopted 

 by the best American makers, A Ivan Clark and Sons, 

 Fauth and Co., Stackpole and Brothers, &c. The accom- 

 panying engraving gives a good general idea of it. The 

 scale may be obtained by remembering that the iron base 

 plate is 2i£ inches by 11^ inches. The barrel is 14 inches 

 long by 7" inches in diameter. The paper used is 23J 

 inches by 13 inches which provides for a lap at the line of 

 junction. There is room for the observations of two hours 

 and forty minutes. The weight employed is fifteen 

 pounds, and usually a double pulley is used to diminish 

 the fall. 



The chronograph can be wound while it is going, with- 



