1) Meninges 2) Meninx 
Two thin layers of fine tissue covering the brain and spinal cord: the pia mater and arachnoid.
(from the article `meninges`) ...remnants of the common origin of the arachnoid and pia mater, and they have the frail structure characteristic of these two of the meninges. The ...
The two delicate layers of the meninges, the arachnoid mater and pia mater (vs. The tough pachymeninx or dura mater), considered together; by this concept, the arachnoid and pia are two parts of a single layer, much like the parietal and visceral layers of a serous membrane or bursa; although separated by the subarachnoid space they are connected v...
(lep″to-mә-nin´jēz) (plural of leptomeninx) the two more delicate components of the meninges: the pia mater and arachnoid considered together; the pia-arachnoid. adj., leptomenin´geal., adj.
Type: Term Pronunciation: lep′tō-mĕ-nin′jēz, lep′tō-mē′ninks Synonyms: leptomeninx
Leptomeninges: The two innermost layers of tissues that cover the brain and spinal cord. The two layers are called the arachnoid mater and pia mater.
[n] - the two innermost layers of the meninges
noun the two innermost layers of the meninges; cerebrospinal fluid circulates between these innermost layers