Antedon with 18-30 (usually 20-23) cirrals; all but first 2-3 are longer than wide and centrally constricted; distal cirrals differing only slightly from proximal; distal halves of cirri only slightly, if at all, curled in preserved specimens, and in lateral view not noticeably wider than proximal halves. First primibrachials relatively long, not more than three times as broad as long, regularly oblong or slightly trapezoidal, with lateral edges usually making a straight line, or a very wide angle with those of the axil. P1 stout but tapering rapidly, with <20 (usually 13 to 15) segments. Disk naked interbrachially.
Clark AH, Clark AM (1967) A monograph of the existing crinoids 1(5). Bulletin of the United States National Museum (82):1-860.