Designed by Arthur Schulze for Ludwig & Mayer in 1926. Smaller sizes have plain caps. From 16 pt upward, the caps are decorated with highlights and thorns. For letters like ‘b’ or ‘k’, there are alternates with extra long ascenders.
Several freebie digitizations exist, including Poseidon (James Fordyce, 1993) and the related Neptun (Dieter Steffmann, 1999, with a larger glyph set, used for the sample), featuring the decorated caps and likely based on a showing in Hoffmanns Schriftatlas (its text includes “Neptun”). Herzog von Graf (Nick’s Fonts, 2000) is a reworking of Poseidon. BigElla (Manfred Klein, 2002) is another wonky freebie interpretation.