As to the _exact position_ of this glottis when at rest, a word or two must be said; for a number of prepositions have been used to describe it. One writer says ‘beneath’ the tongue sheath, others say ‘beyond,’ others again ‘before;’ ‘over,’ ‘above,’ ‘behind,’ ‘in front of,’ have been variously used, and all depending on which way the snake is viewed; but without drawing upon half a score of prepositions to puzzle the reader, as I myself was sorely puzzled until a yawning snake was so kind as to afford me an ocular scrutiny of its lingual arrangements, we can easily comprehend where a passage to the windpipe and lungs must necessarily be, and which, it is clear, is not _under_ the tongue. When a snake’s head is raised, as in crawling up a wall or a tree, the glottis may be said to be ‘beneath’ or ‘under;’ but the general position of a snake being horizontal, the mouth then opened would show you the opening of the tongue sheath _nearest_ to you and to the front; and beyond that, behind, over, or _upon_ the tongue sheath, is another aperture, which is the glottis or entrance to the larynx and trachea or windpipe. So there are in fact two sheaths or tubes lying one upon the other, viz. the tongue sheath, and upon this and parallel with it, the windpipe. After becoming better acquainted with the nature of that tube which had impressed me so strangely, I lost no opportunity of making further observations, and on the following feeding day at the Gardens I saw the air-tubes of several snakes plainly. In September of that year, a new ‘Horseshoe’ snake (_Zamenis hippocrepis_) arrived from Morocco. It was a small and very pretty snake, and while enjoying the privilege of a private inspection, the keeper got its mouth open for me, enabling me to see the glottis, as well as to both see and _feel_ the four upper rows of its beautiful little teeth, closely placed, and as sharp as the finest pins. But the action of the air-tube was very distinct. Probably little _Zamenis_ was breathing harder and nervously under the detention, but no word better describes the formation of the aperture of the perfectly rounded tube, and the movement of it, than the _petite languette_. Subsequently, there were opportunities of observing the air-tube in two of the large African vipers, the ‘River Jack’ or ‘Nose-horned’ vipers (_Vipera rhinosceros_) occupying the same cage. Each struck a guinea-pig and held it. One of them began to eat his before it was quite dead, and had finished it before his friend had begun. In his case, the air-pipe was at the side of his distended jaws. In the other, it projected more than half an inch _beneath_, nearly in the centre.