of Palaeostomatidae, [554]

Peristomial area, [139];

of Caenomorpha and Metopus, [154];

of Bursaria, [155]

Peristomial collar, [142], [156], [157]

Peristomial plate, of Ophiothrix fragilis, [483];

of Endocyclica, [530];

of Cidaridae, [530], [533];

of Echinothuriidae, [530], [535];

of Saleniidae, [537];