Figure 18. Oblique horizontal section through the anterior prosoma of a second instar Phidippus johnsoni. This was a 5 μm Epon section stained with Toluidine Blue, and thus very little shrinkage of structures occurred. Note the smooth pit and staircased (placed in multiple focal planes) receptors of layers I and II in the foveae of the AME, at center. The intrusive pigment at the margins of each AME eye tube is aligned with thin, membraneous structures within the clear matrix. Receptor layer I is most distinct, and nothing can be seen of receptor layers III and IV in this view.