Hello Meg
These eggs were at about 20 days, the substrate I use is vermiculite which I have used for the past 6 breeding seasons. The difference was in the container, I recently moved house and the only thing I had was an exoterra cage, I agree with you that this caused the moisture to evaporate too quickly leading to dehydration, you now how hot it gets here in Durbs'.
I will keep everyone posted on the development of the other eggs in my own post, I always seem to hijack yours. My apologies.
Ciao