jaws, [270];

anus, [259];

nephridium, [254];

habits, [286];

as ectoparasites or commensals, [294], [298], [325];

distribution, [299], [300];

British species, [299], [310] f.;

P. squamata, [309];

elytron, [310];

P. clava, elytron, [310];