[Illustration: _Photo by E. C. Atkinson._
Notwithstanding its name, the blind-worm possesses small, very bright little eyes.]
The Lizard Tribe or Sub-order is notable as containing a greater number of specific forms than any other of the Reptilian groups, no less than 1,700 distinct species being described in the most recently published catalogues. While formerly regarded as constituting a separate and independent order of the Reptile Class, later investigations have demonstrated that lizards are so intimately related through sundry intermediate types with the Snakes that they cannot be recognised as constituting other than a sub-section of the same order. The two groups of the Lizards and Snakes are consequently, and with reference more particularly to their commonly shared scaly armatures, technically distinguished by the appellation of Scaled Reptiles.
[Illustration: _Photo by W. Saville-Kent, F.Z.S._] [_Milford-on-Sea._
The presence of movable eyelids distinguishes this legless lizard from the true snakes.]
[Illustration: _Photo by W. Saville-Kent, F.Z.S._] [_Milford-on-Sea._
Snails constitute the favourite food of the glass-snake.]
While the more typical members of the Lizard Tribe are readily distinguished from the Snakes by the possession of well-developed limbs, a not inconsiderable number of species are altogether devoid of these appendages, or possess them only in a partially developed or rudimentary condition. The BRITISH BLIND-WORM, or SLOW-WORM, constitutes an example of such a legless lizard, although on account of its outward snake-like appearance it is commonly regarded as a snake by the uneducated. In the South European so-called GLASS-SNAKE, or SCHELTOPUSIK, here figured, the snake-like aspect and creeping habits are still more conspicuous, but yet when examined more critically its lizard affinities become apparent. One of the most readily apprehended external characters that serve to distinguish this and the majority of the legless lizards from snakes is the possession by the former of movable eyelids and conspicuous external ear-openings. Among snakes eyelids are invariably absent, the eyes, by way of compensation, being covered by transparent horny plates, which impart to these creatures that peculiar stony stare which undoubtedly constitutes one of the most repulsive features of their tribe. There are, however, a few exceptional lizards devoid of eyelids, though these species do not take a snake-like form.