Note:  Do not rely on this information. It is very old.

Pectinated Rhombs

Pectinated Rhombs are certain rhombic areas on the plates of the Palaeozoic (q.v.) class of Echinoderms known as Cystideae ; these areas are crossed by a, number of grooves pierced by pores. Their function is uncertain; they may be respiratory, reproductive, or both.