variations of, in Endocyclica, [531];

of Echinarachnius parma, [546], [547];

absent in Echinocardium cordatum, [550]

Arm, of Asteroidea, [431], [432], [453];

of Ophiothrix fragilis, [479];

of Ophiuroidea, [481], [491];

of Crinoidea, [580], [589];

of Antedon rosacea, [581];

of Antedon (other species), [594];

of Hyocrinus, [590];