• 1
     Some features of the cranial anatomy, including the chondrocranium, of the burrowing lizard Anniella pulchra are described, mainly from serial sections.
  • 2
     The skull shows marked elongation of the temporal region, reduction of the orbits, loss of the temporal arcades and obliteration of the parieto-occipital angle, so that the skull contours are streamlined.
  • 3
     The cranial kinesis is thought to be mainly of the mesokinetic type.
  • 4
     Basitrabecular processes, menisci and small epipterygoids are present. The parietal bones possess extensive downgrowths which partly enclose the cranial cavity on either side.
  • 5
     The chondrocranium shows great reduction in the orbito-temporal region. A low interorbital septum, narrow planum supraseptale and taeniae marginales are present. There are no pila metoptica or pila accessoria and the taeniae mediales are represented only by embryonic rudiments. There are no discrete optic foramina, the optic nerves passing back to the chiasma above the trabecula communis.
  • 6
     The eyes are small but can hardly be regarded as degenerate; eyelids, nictitating membrane, lachrymal canaliculi and retractor bulbi muscles are present.
  • 7
     The tympanic membrane, tympanic cavity and Eustachian tubes are absent. The columella is massive with a small extra-columella.
  • 8
     Conditions in Anniella are compared with those in other burrowing lizards, especially with Anguis fragilis, the skinks Nessia sp., and Acontias meleagris, and amphisbaenids. The main structural features associated with burrowing adaptation in lizards are described.
  • 9
     In spite of marked burrowing specialization, the cranial anatomy of Anniella resembles that of more typical Sauria in many important respects, and lacks aberrant features such as are present in amphisbaenids.