The darned thing is so bloody small, I have no idea how to separate the upper from lower cortex, so I just squashed an entire lobe under the microscope. One surface was paraplectenchymatous (tiny packed round cells), the other was clearly prosoplectenchymatous (long narrow wavy parallel hyphae). Never dreamed it would be so obvious or easy. (This critical character separates Physciella from the sometimes otherwise identical Phaeophyscia.)