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Show 902 ON THE " RATTLE " OF THE PORCUPINE. [Dec. 11, continuous with the new autumn feather; it did not merely adhere to the tip of this latter, but the shaft was continuous and the barbs were forming at the proximal extremity; 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 autumn 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 cristcita, and pointed out that the organ must be classed functionally in the same category as the rattle of the Rattlesnake and the stridulating organs 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 abroad 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 uttering hoarse guttural grunts, both of which sounds can be heard at a considerable distance. Their proximity is also advertised in another way, namely, by the whiteness of their quills, which when erected in the characteristic fan-like manner are quite conspicuous in the dark and enable the observer to locate the animal accurately, which the crepitation of the quills alone is incapable of doing. Warning or aposematic attributes are characteristic of poisonous or nauseous animals 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, iii spite of their spiny armature, are 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 informed by Mr. Simons, one of the collectors employed in S. Africa by Col. Sloggett, D.S.O., F.Z.S. This correlation between the defensive spine armature and the facile destructibility of Porcupines accounts, 011 the theory of aposemasy, for the advertising characteristics of the animals. rllie 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 conspicuous white blaze by elevating the spines 011 the lumbar area of the back. On the other hand, the North-American Porcupine (h rethizon), and the prehensile-tailed South and Central-American species (Coenclu), which are without the rattle but have the spines t hickly interspersed with hairs, are known to be procryptically coloured amongst the branches and foliage of trees. When, however, the animals are disturbed they raise their spines and become \ isible at once by the display of the white or red colour at their |