Well here's another little embryo photo, taken today. I'm really getting into this! For the record this is Litoria peronii, the Perons Treefrog. Read earlier post.
Bit tricky getting the capsule to show up, required some experimentation with the lighting and positioning to get it right, but I think it paid off.
If you look closely you can see the external gill filaments - little fingery projections behind where the operculum is forming. You can see the eye developing too.
I'm going to call this stage 22.