of Arbaciidae, [538];
of Echinus microtuberculatus, [540]
Peritoneum, of Asterias rubens, [437];
of Holothuria nigra, [567]
Peritrichaceae, [138];
pellicle, [141];
myonemes, [142];
trichocysts, [143];
contractile vacuole and reservoir, [145];
pharynx, vestibule, mode of feeding, [145];