Remarkable for the spiny armature, which is arranged in concentric girdles.
The Greaved Lizard Family includes somewhat over one hundred species. While the majority agree with the teguexin in the possession of well-developed limbs, there are a few retrograde forms in which the hinder limbs are entirely absent or the front ones reduced to mere stumps. These exceptional instances pave the way to the family of the Amphisbænas, in which such or a still lower phase of limb development represents the normal condition. The Amphisbænas are remarkable for their worm-like resemblance, and for the circumstances that they live like earth-worms in burrows, that their eyes are functionless (being concealed beneath the skin), and that they are without ears. Other details of structure indicate a most rudimentary condition of development, and they consequently rank as the lowest group in the Lizard series. Another peculiarity of the Amphisbænas is that, in place of scales, the skin of the body is divided into square segments, which form symmetrical rings like those of worms. In addition to this, these retrograde lizards possess the worm-like faculty of being able to move backwards and forwards in their burrows with equal facility. It is from this peculiar property that their title of Amphisbæna, signifying "moving both ways," is derived. The representatives of this family, including between sixty and seventy species, are widely distributed, being found in America, the West Indies, Africa, and also European countries that border the Mediterranean.
Photo by W. P. Dando, F.Z.S.] [Regent's Park.
ARIZONA HELODERM (POISONOUS LIZARD).
In the warted texture of its skin-surface the heloderm differs conspicuously from other lizards.
While the Teguexins present resemblances in one direction with the Amphisbænas, or Worm-like Lizards, the higher or Monitor-like forms have much in common with the Typical or True Lizards, of which two small but well-known species—the Sand- and Viviparous Lizards—are indigenous to the British Isles. All the members of the True Lizards, numbering some hundred species, are inhabitants of the Old World, becoming scarce, however, towards the far east of the Asiatic Continent. All possess shapely bodies and well-developed limbs with five-toed feet, and are remarkable for the extreme activity of their movements, and in many cases brilliant colouring.
Photo by Scholastic Photo. Co.] [Parson's Green.
WHITE MONITOR.