Peristomium, of Nereis, [248];

of Polychaeta, [263];

of Sabellidae, [336]

Perrier, on Oligochaeta, [367], [385]

Petalostoma, [422], [426], [430], [447]

Petromyzon, host of Gordius, [173]

Petta, intestine of, [271]

Phagocata, [31], [32]

Phalacrophorus, [314]

Phanerocephala, [258], [303]