Florometra with brachials following the third syzygy about as long as broad instead of markedly broader than long. Position of third syzygy irregular, often between brachials 16+17 instead of between 14+15. Proximal pinnulars of oral pinnules with aboral processes but not broadened.
Clark AH, Clark AM (1967) A monograph of the existing crinoids 1(5). Bulletin of the United States National Museum (82):1-860.