Which meninx does not have a space deep to it?

The pia mater is the meninx that does not have a space deep to it. It is the innermost layer of the meninges, closely adhering to the surface of the brain and spinal cord. Unlike the dura mater and arachnoid mater, which have subdural and subarachnoid spaces respectively, the pia mater is directly in contact with the nervous tissue.