There is no article of natural history the ancients have dwelt on more than that of the viper, whether poets, physicians, or historians. All have enlarged upon the particular sizes, colours, and qualities, yet the knowledge of their manners is but little extended. Almost every author that has treated of them, if he hath advanced some truths which he has left slenderly established by proof or experiment, by way of compensation, hath added as many falsehoods so strongly asserted, that they have occasioned more doubt than the others have brought of light, certainty, and conviction. [Illustration: _Cerastes._ _London Publish’d Dec^r. 1.^{st} 1789. by G. Robinson & Co._ _Heath. Sc._] Lucan, in Cato’s march through the desert of the Cyrenaicum in Search of Juba, gives such a catalogue of these venomous animals, that we cannot wonder, as he insinuates, that great part of the Roman army was destroyed by them; yet I will not scruple to aver this is mere fable. I have travelled across the Cyrenaicum in all its directions, and never saw but one species of viper, which was the Cerastes, or Horned Viper, now before us. Neither did I ever see any of the snake kind that could be mistaken for the viper. I apprehend the snake cannot subsist without water, as the Cerastes, from the places in which he is found, seems assuredly to do. Indeed those that Lucan speaks of must have been all vipers, because the mention of every one of their names is followed by the death of a man. There are no serpents of any kind in Upper Abyssinia that ever I saw, and no remarkable varieties even in Low, excepting the large snake called the Boa, which is often above twenty feet in length, and as thick as an ordinary man’s thigh. He is a beast of prey, feeds upon antelopes, and the deer kind, which having no canine teeth, consequently no poison, he swallows whole, after having broken all its bones in pieces, and drawn it into a length to be more easily mastered. His chief residence is by the grassy pools of rivers that are stagnant. Notwithstanding which, we hear of the Monk Gregory telling M. Ludolf, that serpents were so frequent in Abyssinia, that every man carried with him a stick bent in a particular manner, for the more commodiously killing these creatures, and this M. Ludolf recommends as a discovery. And Jerome Lobo, among the rest of his fables, has some on this subject likewise. A cold and rainy country can never be a habitation for vipers. We see, on the contrary, that their favourite choice are deserts and burning sand, without verdure, and without any moisture whatever.