A post-mortem examination would probably have disclosed an imperfectly formed Ovary incapable of bringing Ova to maturity.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
On these fibres the Ova are deposited, and they are then either purposely partly covered with sand by the minnie, or else the particles that are brought down by the current gather over the bundle of fibres and conceal it, excepting one small spot.
"Wild Life in a Southern County"
Richard Jefferies
It would seem as if a current of fresh water were essential to the Ova, and that that is why the opening of the nest is so carefully kept from becoming choked up.
"Wild Life in a Southern County"
Richard Jefferies