Abstract
The extraxial-axial theory (EAT) indicates that the tests of lepidocystids and gogiid eocrinoids are not homologous, and should be assigned different names. In agreement with Nardin et al. (2009), the term "theca" is proposed here for body capsules corresponding to fully devaginated tegmens, while the term "prototheca" is coined here, to describe tests characterised by a partial devagination of the tegmen and thus, intermediate in morphology between a calyx and a theca.