230 REPTILES

developed. The gecko lizards have fleshy plates on
their feet, by which they are enabled not only to run
up perpendicular walls, but even hang downwards on
ceilings. The water lizards are over six feet long, and
have a tail like a saw, with which a deep wound can
be made. One lizard (Amblyrhynchus) lives on the
rocks round the Galapagos Islands, and feeds on sea-
weed. The frilled Australian lizard (Chlamydosaurus)
enters into rivalry with the kangaroos, and hops about
on his hind legs; but the most curious Australian lizard
is the particularly harmless J7oloch, which possesses
the most terrifying exterior of any animal on four
legs. The chameleon is said to go to sleep only one
side at a time, which is not an easy matter to prove.
Like several other lizards, it has the power of
changing its colour at will to suit its surroundings.
The Amphisbena is a degenerate lizard, living under-
ground, and very rudimentary in structure ; another
rudimentary lizard is the blindworm, which has no
legs visible outside the skin. One lizard, the tuatera,
or Sphenodon, has an order all to itself, Rhyncho-
cephalia, being the last living representative of a
group at least as old as the Trias, which, according
to Baur, ‘are certainly the most generalised group of
all reptiles, and come nearest in many respects to
that order of reptiles from which all others took their
origin.’ This is the lizard with the rudimentary third
eye, which is represented by the pineal gland in man.
In the Varanus lizards the position of this eye is
marked by a bright scale.

CHELONIA.—The chelonians are the tortoise