This _Labyrinth_ (_Fig. 13._) has a great many _Eminencies_ in it of no determin’d Regular Figure (_Fig. 14._), and is covered with a _Membrane_ full of _Nerves_ and _Blood Vessels_. The _Nerve_ enters from the Brain at a Hole in the middle of this _Cavity_ (_a_, _Fig. 15._). There is no _Cochlea_ in the Ear of the Viper; but the Anterior _Demicircular Canal_ opens into a _Semicanal_, which makes some _Spiral Turns_ in the Fore-part of the _Labyrinth_; in like manner as it is in _Fish_. The _Passage_ for the Air to these Organs is not _Outward_, but, as in some Fish, thro’ the Mouth, between the Upper and Under Jaws, running below the _Second_ of the _Common Bones_. But of _This_, and also of the True Mechanic _Use_ of the aforesaid _Parts_, more hereafter. [Illustration] _Poisonous Animals._ As the _Viper_ is Hurtful by Instilling a Liquid _Poison_ into the Wound made by its Teeth; so likewise are all _Venomous_ Creatures whatsoever, whether they _Bite_ or _Sting_, tho’ there be some difference in the Contrivance of their _Organs_, Mischievous after much the same _Manner_; and mostly for the same good _Use_ and Purpose, that is, in order to Kill their _Prey_. This will fully appear, by Examining the _Instruments_ of Death in several of _Them_. First then, The _Spider_ wh_i_ch lives upon Flies, Wasps, and the like _Insects_, is provided with a hooked _Forceps_, placed just by the Mouth, very sharp and fine; with _this_ he pierces the Flesh of little Creatures caught in his _Webb_, and at the same time infuses a _Juice_ into the Puncture, by which means the Animal being Killed, He sucks out the Moisture from the Body, and leaves it a dry husky Carkass. M^r _Van Leewenhoek_, in his Account of _Spiders_, lately publish’d (38), has, together with the other Parts, by the help of his Glasses, describ’d these _Weapons_, which He finds to lie couched on each side the Mouth, in a Row of Teeth, till they are raised to do Execution. These Rows of Small _Teeth_ are design’d to hold the Prey, that It may not escape the Force of the Bite. And in the Convex Part, towards the Point of each _Claw_, He has delineated a little Aperture or _Slit_, thro’ which he supposes the Poison issues out at the same time the Wound is made. This _Situation_ and _Motion_ of these Parts, I have several times view’d; but was never able to discern the _Exit_ or Opening; which, having a just Deference to the Industry and Application of so Nice an Observer in Things of this Nature, I, at first, imputed to my own Unskilfulness in such Enquiries, knowing my _Microscope_ to be very good; till at last, after repeated Trials, I very plainly saw, That nothing dropt out of the _Claws_, which were always dry while the Spider Bit, but that a short, white _Proboscis_ was at the same time thrust out of the Mouth, which instilled a _Liquor_ into the Wound.