These lizards have completely
snake-like bodies; one genus of the group (Chirotes
) has a
pair of small pectoral members, but the rest are apodal. The
integument of the body is not scaly, but its surface is divided
into small rectangular areas arranged in transverse rows. The
tail is exceedingly short, so that the vent is close to the end
of the body.
The numerous procoelous vertebrae have less elliptical
articular faces than those of the typical Lacertilia
. There is
no sacrum, and all the precaudal vertebrae, except the one or
two of the most anterior, have ribs. The representatives of
the chevron-bones in the tail are firmly united with the centra
of the vertebrae. The vertebrae have no zygantrum nor zygosphene. Amphisbaena
has no sternum. Chirotes has a sternum,
but it is not united with the ribs.
The skull, unlike that of Lacertilia
in general, develops no
interorbital septum. In this respect, and in the complete
closure of its anterolateral walls by bone, it resembles the
Ophidian cranium. There is no columella. Post-frontals are
absent, and the squamosal is very small. The quadrate bone
is small, and inclined not only downward, but forward, in a
manner unknown in other Lacertilia
. The two rami of the
mandible are firmly united by suture.
the premaxillae bear two rows of teeth,
one behind the other, and one tooth lies upon the symphysis
of the premaxillae.