Amniotes are a group of animals including birds and reptiles that have adapted to lay eggs that can survive on land. Surrounding the embryo in an amniotic egg is the amnion, a sac of fluid. The allantois provides gas exchange and allows for the removal of waste. The white and shell of the egg retains moisture while keeping water from getting in and still allowing for some gas exchange.
A P Biology 2013 - 2014 