basal plates
From ZooTerms (Dictionary of Invertebrate Zoology)
basal plates: 1. (Echinodermata: Crinoidea) A cycle of 5 aboral calyx plates in primitive stalked crinoids. See also radial plates.
2. (NEMATA) The circular base of the cephalic framework, composed of an annular structure with posteriorly directed rim, the basal ring, and six radial elements.
