NATURAL HISTORY
OF
SERPENTS
PART I.
SECTION I.
I begin with the Division of Serpents, which I distribute into Terrestrial, that live upon Land only; Aquatick, that live in Water; and Amphibious, that inhabit both Elements. Under these I comprehend all the Relatives to the venomous Tribe. But how can Land-Serpents live in Water? I answer, their Bodies are equally formed for both Places.
Among Animals, some breathe by Lungs, and others by Gills, as all sanguineous Fish, (excepting the Whale.) By Gills, I mean those membranous cartilaginous Parts on both sides the Head, whereby they hear and respire: What we call Gills in Fish, are properly their Lungs. Respiration (which is an involuntary Motion of the Breast, whereby Air is alternately taken in and thrown out) is as necessary to Fish as to Land-Animals: In Water, is a great Quantity of Air inclosed, and it is that Air they respire, and by their Gills they separate the Air from the Water, and present it to the Blood, after the same manner as ’tis presented to the Lungs of Land-Animals.
The Gills of Fish have an alternate Motion of Dilatation and Compression; when they dilate their Gills, the Water is taken in; when they contract them, ’tis expelled again. Thus the Water is carried in by the Mouth, and carried off again (stript of its Air) by the Gills, which perform the Office of Lungs. Their sucking Water is Breathing, and their Food as little of Water, perhaps, as other Creatures use.