Plasma-cells, [471]
Plakodes, [283]
Planarians, [475]
Plastron, formation of cranial walls from the, [86], [322], [341]
Plat"ron, of Limulus, [136], [142], [143]
Plat"ron, Palæostracan, compared to trabeculæ of Ammocœtes, [145], [377]
Plat"ron, muscles attached to the, [270]
Plat"ron, of Thelyphonus, [143]
Platyhelmia, [475]