PROTICHNITES (Gr. protos, first; ichnos, footprint).  Applied to certain impressions in the Potsdam sandstone of North America, believed to have been produced by large Crustaceans.

PROTOPHYTA (Gr. protos; and phuton, plant).  The lowest division of plants.

PROTOPLASM (Gr. protos; and plasso I mould).  The elementary basis of organised tissues.  Sometimes used synonymously for the “sarcode” of the Protozoa.

PROTOROSAURUS or PROTEROSAURUS (Gr. protos, first; orao, I see or discover; saura, lizard:  or proteros, earlier; saura, lizard).  A genus of Permian lizards.

PROTOZOA (Gr. protos; and zooen, animal).  The lowest division of the animal kingdom.

PSAMMODUS (Gr. psammos, sand; odous, tooth).  An extinct genus of Cestraciont Sharks.

PSEUDOPODIA (Gr. pseudos, falsity; and pous, foot).  The extensions of the body-substance which are put forth by the Rhizopoda at will, and which serve for locomotion and prehension.

PSILOPHYTON (Gr. psilos, bare; phuton, plant).  An extinct genus of Lycopodiaceous plants.

PTERANODON (Gr. pteron, wing; a, without; odous, tooth).  A genus of Pterosaurian Reptiles.

PTERASPIS (Gr. pteron, wing; aspis, shield).  A genus of Ganoid Fishes.

PTERICHTHYS (Gr. pteron, wing; ichthus, fish).  A genus of Ganoid Fishes.

PTERODACTYLUS (Gr. pteron, wing; daktulos, finger).  A genus of Pterosaurian Reptiles.

PTEROPODA (Gr. pteron, wing; and pous, foot).  A class of the Mollusca which swim by means of fins attached near the head.

PTEROSAURIA (Gr. pteron, wing; saura, lizard).  An extinct order of Reptiles.

PTILODICTYA (Gr. ptilon, a feather; diktuon, a net).  An extinct genus of Polyzoa.

PTYCHOCERAS (Gr. ptuce, a fold; keras, a horn).  A genus of Ammonitidoe.

PULMONATE.  Possessing lungs.

PYRIFORM (Lat. pyrus, a pear; and forma, form).  Pear-shaped.

QUADRUMANA (Lat. quatuor, four; manus, hand).  The order of
Mammals comprising the Apes, Monkeys, Baboons, Lemurs, &c.

RADIATA (Lat. radius, a ray).  Formerly applied to a large number of animals which are now placed in separate sub-kingdoms (e.g., the Coelenterata, the Echinodermata, the Infusoria, &c.)

RADIOLARIA (Lat. radius, a ray).  A division of Protozoa.

RAMUS (Lat. a branch).  Applied to each half or branch of the lower jaw, or mandible, of Vertebrates.

RAPTORES (Lat. rapto, I plunder).  The order of the Birds of
Prey.

RASORES (Lat. rado, I scratch).  The order of the Scratching
Birds (Fowls.  Pigeons, &c.)