Speaking of an American snake (_Pituophis melanoleucus_), in which a similar excitement is observable, Mr. Samuel Lockwood[41] likens it to a ‘mystic wheel.’ ‘The movement consists of numberless units of individual activities,’ he says, ‘and all regulated by and under the perfect control of one will that is felt in every curved line.’ There is some likeness to the ‘thousand personal activities of a regiment of soldiers on their winding way.’ He has watched the creature ‘melting into movements so intricate and delicate that the lithe and limbless thing looks like gossamer incarnate.’ This Pine snake is very smooth, and in the excited actions thus graphically described, it makes no noise like the little Indian viper; but Mr. Lockwood’s words are so appropriate to both snakes that the reader has only to add in imagination the rustling noise that accompanies the quivering echis. Among other of the ophidians remarkable for their hissing is _Psamophis sibilans_, the ‘hissing sand snake,’ a very slender little creature. Several mentioned by the earlier naturalists as ‘the hissing snake,’ are evidently _Heterodons_. Catesby, Lawson, and others mention one as the ‘blowing viper;’ _Blauser_ of the Dutch, also the ‘chequered’ or ‘spreading-adder,’ which leaves no difficulty in identifying _Heterodon platyrhinos_. An American writer indulges in a figure of speech while describing this little Coluber by saying, ‘It emits a succession of hisses, “sibilant sounds,” similar to letting off steam from a small steam engine.’ He at the same time admits that it is harmless and inoffensive in spite of its threatening aspect when flattening its head.’ This is the ‘spread head’ alluded to in chap. xxii., an unfortunate demonstration of alarm which has gained for it its venomous titles. Several of this species have from time to time been added to the collection at the Zoological Gardens, and the chief drawback to their anticipated attractions is that they so soon become tame and peaceful that you can scarcely provoke them to exhibit their reputed power. I have seen one flatten its head so slightly as to be barely noticeable, but I never heard it ‘hiss.’ ‘Its spots become visibly brighter through rage,’ wrote Carver in 1796, ‘and at the same time it blows from its mouth with great force a subtle wind that is reported to be of a nauseous smell.’ Chateaubriand, of course, had something to say of ‘the hissing snake,’ frequent in the warmer States of America. ‘When approached it becomes flat, appears of different colours, and opens its mouth hissing. Great caution is necessary not to enter the atmosphere which surrounds it. It decomposes the air, which, imprudently inhaled, induces languor. The person wastes away, the lungs are affected, and in the course of four months he dies of consumption!’ Of another snake this author says, ‘He hisses like a mountain eagle, he bellows like a bull!’