Figure 2.

Columnar model schema of Herrick (1910), depicting the forebrain of an urodele amphibian, here flipped horizontally and with redrawn lettering. Note Herrick still used in this figure the then standard axial forebrain landmark—the sulcus limitans of His (SL)—, and represented relative to it the dorsal (SDD), middle (SDM) and ventral (SDV) diencephalic sulci. SDM and SDV clearly intersect the SL nearly orthogonally, though described in the text as “longitudinal.” The plane AB was presented as a diencephalic “cross-section.” In ulterior publications of Herrick the SL was no longer represented and the new columnar axis parallel to the SDM/SDV sulci and continuing to a telencephalic end was implicitly established, without ever having been defined by its creator.