Semiorbis Catillifera Guide
Credit: David Burge
  1. Valves weakly arcuate
  2. Dorsal spines present
  3. Apices subcapitate and recurved

Valves are weakly arcuate with recurved, subcapitate apices. Transapical striae are separated by externally thickened transapical costae, forming spines at the dorsal margin.