part of preceded by NF stage 62 NF stage 63 Nieuwkoop and Faber stage 63, corresponding to a tadpole of age about 51 days at 22-24 Celsius and having the following external morphological criteria: Head narrower than trunk. Tentacles mostly disappeared. Corner of mouth at level of caudal border of eye. "Larval aorta" and thymus gland no longer externally visible. Operculum closed. Adult skin areas on abdomen and lower jaw separated by narrow band of larval skin. Forelimb at level of anterior half of heart. Fin mostly perforated near anus. Tail still slightly longer than body. xenopus_developmental_stage XAO:1000075 climax stage NF stage