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The occurrence of parietal eyes among lizards (Suborder Lacertilia) was determined by examining museum specimens and noting the presence of a parietal spot. The parietal spot is a reliable indication of the presence of an underlying parietal eye. The parietal eye is absent in Dibamidae, Pygopodidae, Helodermatidae, Lanthanotidae, Anelytrop- sidae, Gekkonidae, and Teiidae. It is present in most members of Xantusiidae, Scincidae, Cordylidae, Lacertidae, Varanidae, Anniellidae, Anguidae, Xenosauridae, Iguanidae, Agamidae, and Chameleontidae.
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Gundy et al. (1976) studied this question.
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