Turbinoliidae, [398]
Tylostyle (a style in which a knob surrounds the origin), [224]
Tylotoxea (a rhabdus of which one actine is tylote or knobbed, the other oxeate, the latter directed towards the surface of the Sponge), [224]
Tyrosin, [15]
Uexküll, on function of pedicellariae of Echinus, [508];
on physiology of nervous system of Echinoidea, [519];
on vision of Echinoidea, [522];