Sigma

Definition

In D.; a C‐ or S‐shaped microsclere, usually smooth (e.g., genus Mycale); the ends of a s. may be equipped with an external serration (e.g., serrated sigma of subgenus Mycale [Paresperella] serrulata) or microspination (e.g., genera Biemna, Neofibularia, Sigmaxinella); s. can be flagellated (e.g., Mycale [Naviculina] diversisigmata and subgenus Haliclona [Flagellia]); compare with anthosigma.

Synonyms

Bihamate (no longer in use).

Photos