Parental care in S. annulatus. (a) mother and partially hatched clutch showing both eggs and unpigmented altricial hatchlings. (b) Late clutch photographed in the field with well-developed young (the pale colour of the mother most likely indicates she was still skin feeding). (c) Young aggregating around the exposed vent on the elevated body terminus of their mother. (d) View of the lower jaw of a nestling (120 mm total length) showing alternating dental tooth rows. Scale bar, 1.20 mm. (e) Detail of two dentary teeth. Scale bar, 120 μm. Histological comparison of the skin of (f) non-brooding and (g,h) brooding females showing differences in structure and histochemistry. In the latter the epidermis is full of inclusions stained in black after osmium tetroxide and Sudan black B treatment (g,h). E=epidermis, D=dermis, Sc=stratum corneum. Scale bar, 120 μm.