Chemical composition and structure of the eggshell of three oviparous lizards

We investigated the structure of the eggshells of the oviparous scincid lizards, Lampropholis guichenoti and L. delicata, and the agamid Physignathus lesueurii. The eggshells of all three species consisted of an outer calcareous layer, a fibrous shell membrane, and an inner boundary layer. The eggshells of P. lesueurii had an additional amorphous layer between the calcareous and fibrous layers. The calcareous layer of all shells was relatively thin and contained calcium carbonate in the form of calcite, typical of oviparous squamates. The multilayered fibrous shell membrane constituted the majority of shell thickness. The calcareous layer contained the majority of inorganic ions, with calcium and magnesium being present in detectable quantities. Calcium carbonate crystals were also found on the inner boundary layer of the P. lesueurii shells. This phenomenon has only been described for one other species, the Tuatara.