Asymmetric Biraphid
Seminavis
- Valves strongly dorsiventral
- Raphe displaced laterally
- Lineolae present
- Girdle bands hyaline
Valves are semi-lanceolate with a curved dorsal margin and a more or less straight ventral margin. The dorsal mantle is well developed, whereas the ventral mantle development is minimal. Areolae are lineolate, slit-like, and apically elongated, that is, they are lineolae. Internal hymenes are present. The dorsal and ventral striae are...