After thus moralizing to the unheeding lacertines, it was with secret gratification that one heard Professor Huxley, in his Lecture on ‘Snakes’ at the London Institution, Dec. 1, 1879, say—as nearly as I can remember—‘In evolution or a gradual change, the lizard found it profitable to lose its legs and become a snake; all modifications are an improvement to the creature, putting it in a better condition.’ In this ‘better condition,’ therefore, does the slow-worm find itself, when it glides noiselessly, and almost without stirring a blade of grass, into its burrow. In other lizards one may sometimes observe that the _hind_ legs are most used in scratching and pushing the earth away. Thus, in the constricting snakes—these descendants of some pre-ophidian lizards—the unused limbs have become obsolete; and the spine, gaining strength with increased action, has at length become to the constrictors their hands, feet, arms, and legs, and endowed with those wondrous capabilities which were described in chap. xii. To return to the integument. As one of its developments, the hood of the cobra may be included in this chapter, the skin here exhibiting its extensile or expansive construction. It is the longer ribs, about twenty pairs nearest the head (see p. 33), which really do form the hood. These anterior ribs, gradually increasing in length and decreasing again, are not connected with the ventral scales in the same way as those on which the snake progresses, but can be elevated or expanded in the manner familiar to the reader; they then support the extended skin exactly in the way that the ribs of a lined parasol support the fabric; only while the ribs of the parasol spring from a common centre, the ribs of the cobra are attached to its vertebræ, requiring no other agency than the will of the owner. The action of the ribs as expressive of emotion, in several species of snakes, was mentioned page 150. In the ‘hooded’ snakes (_naja_), it is seen in an extreme degree. Facing you, the angry cobra displays these umbra-like expanded ribs, while the form of the ‘neck’ or vertebral column in the centre is prominently perceptible. When at rest, they all lie flat one over the other, like the ribs of a closed parasol. In the way of external peculiarities the ‘gular fissure’ may be mentioned. It is merely a slight groove or crease extending from the chin longitudinally under the throat for a few inches or more, according to the size of the snake; a sort of wrinkle (_fosse_) to admit of expansion during the swallowing of prey. Externally snakes have no indication of ears; therefore, in the way of integument, there is nothing to describe in their organ of hearing. But the eye covering is a beautiful and wonderful arrangement.