Tetracyclus Glans Guide
Credit: Ian Bishop
  1. Central inflation large
  2. Costae coarse
  3. Valve ends rounded, with apices pointed
  4. Sternum narrow
  5. Septum present

Valves are ellliptic-lanceolate with a large central inflation and rounded to pointed apices. The costae are thick and evenly spaced at 2-3 in 10 ┬Ám. The axial area is narrow and linear, sometimes with poorly defined margins. Girdle bands contain septa that extend from alternating ends in adjacent bands.