To examine the developmental timing of HGC appearance and disappearance, we followed eggclutches throughout development, inducing early hatching of a subset of embryos and allowing them to develop as tadpoles in water for comparison with their age-matched siblings developing in the egg.The data presented come from multiple developmental series performed over the course of several years.Each developmental series followed two or three clutches of eggs through development, and specimens were collected at 4, 8, 12 or 24 h intervals, beginning at 2 or 3 days and ending at 6 or 7 days.Eggs collected in 2015 were subjected to warmer ambient temperatures, owing to El Niño, and development in that year was slightly accelerated compared with other years(Warkentin et al., 2017).