habitat, [47];
classification, [50]
Protractor muscles of Aristotle's lantern, [526]
Protriaene (a triaene in which the cladi [branches] point forwards or in the opposite direction to the rhabdome or shaft), [224]
Prouho, on transverse fission in Gonactinia, [371] n.;
on gemmiform pedicellariae of Echinoidea, [509];
on habits of Dorocidaris papillata, [535]
Prunoidea, [77]
Prunophracta, [78]