Though so rarely mentioned in popular books on snakes, this surprising modification of the breathing apparatus was described by the indefatigable Dr. Edward Tyson, on his dissection of the first rattlesnake that fell into the hands of the Royal Society, 1683, and whose paper on the _Vipera caudisona_, as he named it, is quoted in chapters xvi. and xx. ‘Over the tongue did lye the _larynx_, not formed with that variety of cartilages as is usual in other animals, but so as to make a rime or slit for receiving or conveying out the air. Nor was there any epiglottis for preventing other bodies from slipping in, this being sufficiently provided for by the strict closure of it.’[38] Dr. Tyson examined only a dead specimen, and could not therefore witness the action observable in life; but his remarkable accuracy in describing the parts will be evident in comparing what he said with Dumeril, who did observe the living reptiles. The confusion which sometimes occurs in distinguishing the parts may be also explained by the less complicated structure of the tube, which in higher animals presents the nicer distinctions of the parts, glottis, epiglottis, larynx, etc. ‘Il n’y a pas de véritable larynx, une petite languette mobile qui s’ajuste, sur l’ouverture linéaire; c’est la glotte.... La glotte, située au-dessous de la victime, se porte en avant, et l’acte de respiration ne se trouve point empêché. C’est que nous avons indiqué à l’article de la déglutition; car on voit distinctement alors la glotte se fermer et se délater.’[39] This _petite languette_ became a new object of curiosity, and soon came fresh opportunities for observation, namely, when some of the larger snakes were engaged in yawning. On account of its extreme mobility, you do not always detect the form of this little point on the upper lip, which as often as not presents a rounded opening; but occasionally the little tongue—which can be nothing but an apology for an epiglottis—is very distinct, and may be compared with the moveable, pointed snout of some of the large pachyderms, or, still better, with an exactly similar formation at the end of the elephant’s trunk, and which, though for a different purpose, moves similarly.