FIGURE 4 in A new form of Elongatoolithidae, Undulatoolithus pengi oogen. et oosp. nov. from Pingxiang, Jiangxi, China

FIGURE 4. Eggshell microstructure of Undulatoolithus pengi oogen. et oosp. nov. Scale bar: 400 µm. A-C, Radial thin sections through eggshell, A, showing the cone layer and the columnar layer, gradational boundary between the two layers and undulating appearance of ornamentation (short white lines showing the boundary of the cone layer and the columnar layer, and the ornamentation); B, showing the undulated ornamentation; C, enlargement of in A, showing the closely packed and conical cones; D, Tangential section through eggshell near level of the boundary between the cone layer and the columnar layer, showing the interval between cones and pores; E, Tangential section through eggshell within columnar layer, showing the oval or elliptical pores (arrows).