Very similar also to the manner of the puff adder is that of _Vipera rhinosceros_, one of the largest African poisonous serpents, known as the ‘River Jack,’ being fond of water. One of these was in the London collection for several years, and I observed that whenever disturbed, its body swelled considerably, while the ‘hissing,’ or expulsion of breath, alternated with this expansion. Snakes, like other animals, probably differ in temper or in nervousness; for while some are noted hissers, others hiss only on great provocation, and others, again, not at all. One remarkable example of a non-hissing snake, though from no amiability of temper, is the little carpet viper of India (_Echis carinata_). Unless you were positively assured by learned authorities that this exceedingly irritable little viper never hisses, you would scarcely believe your ears, so sibilant is the sound it causes by rustling its scales together. Sir Joseph Fayrer, in the _Thanatophidia_, describes this as a very fierce and aggressive little viper, always ready to attack and be on the defensive. It throws itself into a double coil, and its agitated motion causes the rough, carinated scales to rub against each other, and make a sound like hissing, but ‘_it does not hiss_.’ This rustling is very much like the sound of the crotalus rattle, and the dry scales must be raised in a sort of way, or ruffled, as an alarmed hen ruffles her feathers. ‘The outer scales are prominent, and at a different angle to the rest,’ says Fayrer. It generally lies coiled in a compact form, often like a ‘w,’ as may be seen in the frontispiece, with its head in the centre, but always towards the point of supposed danger, which in a cage is facing the spectator. Curious and wonderful is the agitation into which this carpet snake throws itself when disturbed, every inch of it, excepting the head, in motion. The head retains its fixed position, the eyes intently keeping guard, while the body moves in every conceivable curve, like wheels within wheels, yet retaining the same outline, or occupying the same place and space, though every muscle must be in activity. One can liken this behaviour only to what is seen in the blending of liquids of different densities. As you look down into a glass containing one fluid while drop after drop of another is falling, you perceive fresh currents and curves in every direction. Watching one of these, it has changed places with another, you lose trace of it, each drop is lost in the commingling of the whole. So it is with this wonderful little echis. It is almost impossible to follow with the eye any one portion or coil of its moving length; but each inch changes places and mingles with the rest, like blending fluids.