902 ON THE " RATTLE " OF THE PORCUPINE. [DeC. 11, 



continuous with the new autumn feather ; it did not nievQly 

 adhere to the tip of this latter, but the shaft was continuous and 

 the barbs were forming at the proximal extremit}^ ; the white 

 tip of the winter feather formed also the light base of the summer 

 feather. The summer feather was rather shorter than in the 

 normal condition, and possibly was not fully grown when the 

 autximn moult intervened. 



Mr. R. I. Pocock, F.Z.S., Superintendent of the Gardens^ 

 exhibited the rattle formed of modified quills in the tail of a 

 Porcupine, Hystrix cristata, and pointed out that the organ must 

 be classed functionally in the same category as the rattle of the 

 Rattlesnake and the stridulating oi^gans of ^some Scorpions and 

 large Spiders, that is to say, its use was aposematic. He continued 

 as follows : — The behaviour of Porcupines at night when prowling 

 a,broad is quite different from that of most nocturnal animals. 

 Instead of being silent in their movements like the latter, they 

 seem to make as much noise as possible, rattling their quills and 

 littering hoarse guttural grunts, both of which sounds can be 

 heard at a considera,ble distance. Their proximity is also advertised 

 in another way, namely, by the whiteness of their quills, which 

 when erected in the characteiistic fan-like manner are quite 

 conspicuous in the dai-k and enable the obsei-ver to locate the 

 animal accura.tely, which the crepitation of the quills alone is in- 

 capable of doing. Warning or aposematic attributes are charac- 

 teristic of poisonous or nauseous animaJs which nevertheless may 

 be readily killed or damaged by the attack of more powerful 

 animals ignorant of the protective attributes of their prey, and of 

 the risk of injury they themselves run in attempting to seize it. 

 Porcupines, in spite of their spiny armature, aie easy to kill on 

 account of the extreme thinness of the skin which can be torn to 

 shreds with the greatest facility. A dog trained to the work will 

 shake one to pieces in a few seconds when he has once taken hold 

 below or in front of the spiny area, as Mr. Pocock has been in- 

 formed by Mr. Simons, one of the collectoivs employed in S. Africa 

 by Col. Sloggett, D.S.O., P.Z.S. This correlation between the 

 defensive spine armature and the facile destructibility of Porcu- 

 pines accounts, on the theory of aposemasy, for the advertising 

 characteristics of the animals. 



The same explanation must be extended to the Brush-tailed 

 Porcupines [Atherura), of Africa and India, which also possess 

 rattles formed of modified quills on their tails and display a con- 

 spicuous white blaze by elevating the spines on the liunbar area 

 of the back. On the other hand, the North-Ameiican Poi^cupine 

 (^Brethizoii), &nd the prehensile-tailed South and Central- Ameiican 

 species (Goendu), which are without the rattle but have the spines 

 thickly inteispei'sed with hairs, are known to be procryptically 

 coloured amougst the branches and foliage of trees. When, how- 

 ever, the aninials are disturbed they raise their spines and become 

 visible at once by the display of the white or red colour at their 



