Ere concluding this chapter, one slight exception to the extremely ‘simple’ spinal column must be named. This is that certain families, more nearly allied to the lizards, or most far removed from the vipers, have rudiments of pelvic bones, or those which in bipeds connect the legs with the trunk. In a few families there is even a pair of these rudiments externally, though only in the form of a spur or claw, as seen in the boa constrictor, the pythons, and some of the blindworms, and usually more developed in the male.
There is, however, the true skeleton of a claw beneath the skin, composed of several bones, and presenting somewhat the form of a bird’s claw, hinting at the common ancestry between snakes and lizards. These spurs, though mere vestiges of limbs, must still be of some use to the large constrictors when climbing trees and hanging from the branches. They are found in the boa, python, eryx, and tortrix, four groups which approach the lizard characteristics; also in Boa aquatica, the anaconda.
CHAPTER XIII.
FRESH-WATER SNAKES.
THE frequent allusion to water snakes in the preceding chapters seems to render this a suitable place to describe them more in detail; and among them are of course the sea snakes, and ‘The Great Sea Serpent’ must not be omitted.
In many books on natural history, particularly if herpetology occupy any space, we find the subject wound up with a chapter on ‘The Sea Serpent,’ forming a sort of apologetic little addendum, as if the creature of questionable existence must claim no space in the heart of the volume, yet is not quite so unimportant as to be omitted altogether.
On the part of some other authors, a total and summary dismissal of the ‘monster’ is apt to exclude with it any reference to the smaller sea snakes, whose actual existence is therefore a fact less known than it should be; and many persons, seeing the doubt cast upon the celebrated individual whose reputed reappearance on the prorogation of Parliament has become an annual joke, conclude that all sea snakes are similarly mythical.