But the perfection of mechanism culminates in the viper fangs; and reasoning from analogy, the intensity of poison in their glands also. When at rest, these lie supine along the jaw, but can be ‘erected,’ _i.e._ sprung down, for use by a special muscle. The two fangs above the dotted illustration of viperine dentition (p. 355) show both positions. Nicholson affirms that the Indian viper Daboia can inject as much poison in half a second as a cobra can in three seconds; ‘that whereas a cobra’s virus flows in small droplets, the viper’s runs in a fine stream.’ Though a much smaller snake than the cobra, Daboia’s fangs are nearly double the size, as may be observed by comparing the figs. _C_ and _D_ (p. 349). There seems reason to believe also that this viper (which in its features Fayrer considers a true Indian type) can inflict injury with more than the pair of functional fangs. ‘In reference to the connection of the poison fangs with the maxillary bones,’ says this learned experimentalist, ‘I would note that second or even third supplementary fangs may be anchylosed with the principal one to the maxillary bone. I have before me the skull of a Daboia, for which I am indebted to Mr. Sceva, in which this is the case; and where there are five well-developed poison fangs on each side, of which on one side two are anchylosed to the bone.’[98] (Described by Mr. Tombes, _Phil. Trans._ vol. clxvi. p. 146.) This may explain what we so often read in the description of venomous snakes found with two, three, or more fangs on each side. In my _Lachesis_ two were distinctly visible before I began to dig for those hidden in the loose membrane, of which there seemed an abundance, and I am nearly certain that the second one had its own particular sheath. The spirit in which the specimen had so long been immersed, as well as my awkward probings, forbid me to speak with certainty regarding this second sheath. After one of his rattlesnake bites—twenty days after—Dr. Stradling informed me by letter: ‘My little _durissus_ is shedding its skin; but when that is over, I shall certainly examine its mouth. Now that my arm is on the verge of ulceration, I find what I had not noticed before, that each puncture is _double_—two large ones and a tiny second one, about 1/12 inch behind each, standing out in black relief against the scarlet skin.’