Besides this, when the Viper bites, It strikes in the Fangs to the very Root; and thus the _Vesiculæ_ are still more squeezed for the Discharge of the Liquor.
It is worthy our Observation, that the Viper can move the Jaw Bones on _one_ side without moving Those on the _other_, for they are not joined together at the Extremes as in other Animals; which Contrivance is very beneficial to it in the _swallowing_ its Prey; in that, while the Teeth on one side stand unmoved, and fixt in the Flesh to hold it, _Those_ on the other side are brought forward, to draw it in farther, then they keep it fast till the former Jaws advance again in their _Turn_. Thus they act successively, and force the Animal intire (there being no _Dentes Incisivi_ or _Molares_ to divide it) into the _Œsophagus_, whose Muscular Fibres are very Weak, and can help but little in the Business.
It may not be amiss to conclude these _Remarks_ with a short _Hint_ concerning the _Organs of Hearing_; Mr. _Charas_ (who is however followed by others in _it_) having, as we mention’d before, Entertain’d a very absurd Opinion about _Them_.
_These_ then are placed in the _Temporal_ Bones, as in other Animals, and consist of _One_ long, small _Bone_ (_Vid._ _Fig. 11._), like _that_ of _Birds_, whose Extremity is broad, like the _Basis_ of the _Stapes_ in _Man_, and situated upon a little _Hole_ which opens into the _Labyrinth_; and besides of _three Demicircular Canals_ (_Fig. 12. a b_) which also open into the _Labyrinth_.
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.