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THE SKULL OF REPTILES
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Fig. 56. Lacertilian skull: A, B, C, Amphisbaena, from above, below, and the side. Five halves natural size. D, side view of atlas and axis.
The temporal fossa, normally (Fig. 55 a) bounded above by the parietal, below by the tabular, squamosal, and postorbital, may be wholly absent, as in the Amphisbaenidae (Fig. 56 a), completely roofed over by dermal bones, or obliterated by the union of the temporal arch with the parietal.
The premaxillae may be paired or fused; in the mosasaurs (Fig. 54 c) the united bone is fused with the nasals posteriorly, or the latter may be absent or vestigial. The lacrimals are always small,
