There remains yet much more to describe in connection with the poison fang, which might come in the present chapter; but as the two following will treat of the Viperidæ and the Crotalidæ—the dentition being the same in both—the viperine fangs shall claim further space under those heads. These three consecutive chapters, and also chap. xxii. on some exceptional forms of dentition, must necessarily be somewhat blended; but I divide them thus in order to present the distinct families more clearly, and render the subject less tedious to the reader.
CHAPTER XX.
VIPERINE FANGS.
THOUGH the ensuing chapter will be devoted more exclusively to the Crotalidæ or rattlesnakes, it were well to repeat here that the two families Viperidæ and Crotalidæ comprise the sub-order of Ophidia ‘VIPERINA,’—those that have the isolated, moveable fangs, the term isolated having reference to the functional fang only. It may appear incongruous to present the illustration of a viperine jaw with a whole cluster of fangs, while affirming that there is the one pair only; but the pair in use are ‘solitary,’ because the jaw bears no simple teeth, as in those with fixed or permanently erect fangs.
The first observation of the mobility of the viperine fang and its peculiar structure is ascribed to Felix Fontana,[99] an eminent naturalist and Professor of Philosophy at Pisa, in the eighteenth century. He formed the cabinet of Natural History at Florence, and died 1805, in his 75th year. But the mobility or action of rattlesnake fangs was known long prior to Fontana, and he probably borrowed the expression ‘dog-teeth’ from the old Virginia writers who thus called the fangs. Purchas (1614), quoted in chap. xvi., describes ‘venomous Serpentes, one ten Spannes long, with great Tuskes, which they hide and stretch out at pleasure.’[100] And again, in describing ‘foure kinds of venomous Snakes. The first is greatest, Jararacucu, that is great Jararaca, and they are ten Spannes long: they have great Tuskes hidden in the Mouth along their Gummes, and when they bite they stretch them like a Finger of the Hand; they have their Poyson in their Gummes, their Teeth crooked, and a Stroake vpon them whereby the Poison runneth. Others say they have it within the Tooth which is hollow within. It hath so vehement a Poison that in foure-and-twentie Houres and lesse it killeth a Man.’[101]
There can be no doubt but that viperine fangs are here described, those belonging to the South American Crotalidæ, under their vernacular but then their only names. Dr. Ed. Tyson, who dissected the first rattlesnake that was handed over to science (p. 275), quite understood the mobility of the fangs, and of the existence of supplementary teeth, though not fully comprehending the nature of these latter; which ‘I could not perceive were fastened to any Bone, but to Muscles or Tendons there. These Fangs were not to be perceived upon first opening the Mouth, they lying couched under a strong Membrane or Sheath, but so as did make a large Riseing there on the Outside of the lesser Teeth of the Maxilla’ (meaning the reserve fangs), ‘but at Pleasure when alive they could raise them to do Execution with, not unlike as a Lyon or a Cat does its Claws.’[102]
He found seven reserve fangs on each side; and though they were not, as he tells us, ‘fastened to any bone,’ the illustration represents them growing in regular order according to size in the jaw.