Lampropholis spp. The eggshells of Lampropholis guichenoti and L. delicata are similar in structure and so are described together. The shell consists of an outer calcareous layer, a fibrous shell membrane, and an inner boundary layer. (A) Outer surface of the eggshell showing the calcareous layer, which appears rough at low magnification. Scale bar = 0.1mm. (B and C) Closely abutting calcareous sections (c) of variable size visible on the outer calcareous layer (B), giving the appearance of being continuous in most shells (C). Scale bar = 10 μm. (D) Unstructured pore-like openings (arrow) on the surface of the calcareous layer. Scale bar = 10 μm. (E) Wave-like curves are present at regular intervals on the surface of the outer calcareous layer. Scale bar = 10 μm. (F) Cross-sectional view. The curvature of the outer calcareous layer (c) is visible. The fibrous layer (f), below the calcareous layer, comprises the majority of shell thickness. The inner boundary (b) layer is seen covering the inside of the shell in the bottom left-hand corner of the figure. Scale bar = 10 μm. (G) Fibrous layer as viewed from the inside surface of the shell (i.e., the internal area that houses the embryo). The fibers occur in layers with alternating direction. Scale bar = 10 μm. (H) The thin organic amorphous boundary layer (b), which underlies the fibrous layer (f), on the innermost side of eggshells. The shape of the fibers is visible through the boundary layer (arrow). Scale bar = 10 μm

Physignathus lesueurii. The eggshells consist of an outer calcareous layer with an underlying fibrous shell membrane and an inner boundary layer. An amorphous layer between the calcareous and fibrous layer was visible in one shell. (A) The outer calcareous layer which faces the external environment is composed of a thin crust of closely apposed calcareous rosettes on the surface of the eggshells. Scale bar = 0.1 mm. (B) Unusual and isolated calcareous rosette found on the outer surface of a hatched shell with an organic amorphous layer (a) separating the calcareous and fibrous layers visible below. This is probably due to incomplete calcification of the shell. Scale bar = 0.1 mm. (C) The outer calcareous layer of fresh and hatched eggshells of one clutch consist of flattened and closely apposed calcareous sections (c) of variable size visible on the surface of the calcareous layer. Scale bar = 10 μm. (D) Furrows are visible on the outer calcareous layer dividing the surface of the shell into sections of various size, each appears to have a central smooth (s) area surrounded by a rougher (r) area. Scale bar = 1 mm. The central area of each section, as viewed under higher magnification, has closely abutting calcareous sections (c) giving the appearance of being smooth (E: scale bar = 10 μm), and is surrounded by a rough pitted area (F: scale bar = 0.1 mm). (G) Cross-sectional view with the inner boundary layer (b) that faces the internal environment of the egg uppermost and the outer calcareous layer (c) facing the bottom of the figure. The fibrous layer (f) between the boundary and calcareous layers comprises the majority of shell thickness. Scale bar = 0.1 mm. (H) Boundary layer on the inside of the eggshell (b) with the fibrous layer visible (f). The fibers closest to the boundary layer (arrow) are more flattened in shape and more compact than fibers deeper in the eggshell. Scale bar = 10 μm

Physignathus lesueurii. The eggshells consist of an outer calcareous layer with an underlying fibrous shell membrane and an inner boundary layer. An amorphous layer between the calcareous and fibrous layer was visible in one shell. (A) The fibrous layer of a hatched shell. The fibers are laid down in layers with alternating direction similar to a laminar series, with spaces between parallel fibers. Scale bar = 10 μm. (B) The fibrous layer of a fresh shell. The spaces between fibers in fresh shells are smaller than that of hatched shells (fresh shells, mean = 1.21 μm; hatched shells, mean = 3.73 μm). Scale bar = 10 μm. (C) The inner boundary layer that faces the internal environment of the egg and appears smooth in most shells. Scale bar = 10 μm. (D) The inner boundary layer is a thin layer through which the fibers (arrow) of the shell membrane are visible. Scale bar = 10 μm. (E) The inner boundary layer with visible discontinuities (arrows), possibly due to damage during preparation. Scale bar = 10 μm. (F) Calcium deposits (arrows) resting on, but not penetrating, the inner boundary layer (b) of the eggshell of most fresh and some hatched eggs. On the left-hand lower corner, the cross-section of the shell is visible with the fibrous layer (f) making up most of the thickness. Scale bar = 0.1 mm. (G) Cross-sectional view showing distinct infolding (arrows) of the calcareous layer (c) in a fresh shell. This was seen in two shells of fresh eggs from different clutches with both the calcareous and fibrous layers furrowed. The inner boundary layer (b) is visible in the lowermost section of the figure. Again, the fibrous layer (f) can be seen to constitute most of the thickness of the shell. Scale bar = 0.1 mm