fission, [147];

conjugation, [151];

peristomial collar, [156], [157]

Perkins, [232] n., [290]

Peronella, [549]

Peronium, [295]

Perrier, on classification of Asteroidea, [461]

Persian Tick, [121]

Petal, of Echinarachnius parma, [545];

of Fibularidae, [549];