Ulnaria Capitata Guide
  1. Valves linear and elongate
  2. Apices spathulate
  3. Striae radiate at apices
  4. Rimoportulae at apices

Valves are linear and elongate. Valve margins are parallel, except at the apices, which are spathulate. Striae are parallel and evenly spaced throughout the valve, becoming radiate at the apices. A rimoportula is present at each apex. A central area is absent.