Amphora delphinea minor guide
  1. Valves with nearly parallel margins
  2. Raphe extends from near ventral margin to dorsal side
  3. Fascia dorsal, rectangular

Valves with nearly parallel margins. Valves at the lower end of the size range are more rounded on the dorsal side. Apices are bluntly rounded, and positioned toward the ventral side. The raphe runs from near the ventral margin to around the dorsal side. The fascia is distinctly rectangular and positioned dorsal to the central nodule.