PHANEROGAMS (Gr. _phaneros_, visible; _gamos_, marriage). Plants which have the organs of reproduction conspicuous, and which bear true flowers.

PHARYNGOBRANCHII (Gr. _pharugx_, pharynx; _bragchia_, gill). The order of Fishes comprising only the Lancelet.

PHASCOLOTHERIUM (Gr. _phaskolos_, a pouch; _therion_, a beast).

A genus of Oolitic Mammals.

PHRAGMACONE (Gr. _phragma_, a part.i.tion; and _konos_, a cone).

The chambered portion of the internal sh.e.l.l of a _Belemnite_.

PHYLLOPODA (Gr. _phullon_, leaf; and _pous_, foot). An order of _Crustacea_.

PINNATE (Lat. _pinna_, a feather). Feather-shaped; or possessing lateral processes.

PINNIGRADA (Lat. _pinna_, a feather; _gradior_, I walk). The group of _Carnivora_, comprising the Seals and Walruses, adapted for an aquatic life. Often called _Pinnipedia_.

PINNULae. (Lat. dim. of _pinna_). The lateral processes of the arms of _Crinoids_.

PISCES (Lat. _piscis_, a fish). The cla.s.s of Vertebrates comprising the Fishes.

PLACOID (Gr. _plax_, a plate; _eidos_, form). Applied to the irregular bony plates, grains, or spines which are found in the skin of various fishes (_Elasmobranchii_).

PLAGIOSTOMI (Gr. _plagios_, transverse; _stoma_, mouth). The Sharks and Rays, in which the mouth is transverse, and is placed on the under surface of the head.

PLATYCERAS (Gr. _platus_, broad; _keras_, horn). A genus of Univalve Molluscs.

PLATYCRINUS (Gr. _platus_, broad; _krinom_, lily). A genus of Crinoidea.

PLATYRHINA (Gr. _platus_, broad; _rhines_, nostrils). A group of the _Quadrumana_.

PLATYSOMUS (Gr. _platus_, wide; _soma_, body). A genus of Ganoid Fishes.

PLEISTOCENE (Gr. _pleistos_, most; _kainos_, new). Often used as synonymous with "Post-Pliocene."

PLEUROTOMARIA (Gr. _pleura_, the side; _tome_, notch). A genus of Univalve sh.e.l.ls.

PLIOCENE (Gr. _pleion_, more; _kainos_, new). The later Tertiary period.

PLIOPITHECUS (Gr. _pleion_, more; _pithekos_, ape). An extinct genus of monkeys.

PLIOSAURUS (Gr. _pleion_, more; _saura_, lizard). A genus of Plesiosaurian Reptiles.

POLYCYSTINA (Gr. _polus_, many; and _kustis_, a cyst). An order of _Protozoa_ with foraminated siliceous sh.e.l.ls.

POLYPARY. The hard chitinous covering secreted by many of the _Hydrozoa_.

POLYPE (Gr. _polus_, many; _pous_, foot). Restricted to the single individual of a simple _Actinozoon_, such as a Sea-anemone, or to the separate zooids of a compound _Actinozoon_. Often applied indiscriminately to any of the _Coelenterata_, or even to the Polyzoa.

POLYPORA (Gr. _polus_, many; _poros_, a pa.s.sage). A genus of Lace-corals (_Fenestellidoe_).

POLYTHALAMOUS (Gr. _polus_; and _thalamos_, chamber). Having many chambers; applied to the sh.e.l.ls of _Foraminifera_ and _Cephalopoda_.

POLYZOA (Gr. _polus_; and _zoon_, animal). A division of the _Molluscoida_ comprising compound animals, such as the Sea-mat--sometimes called _Bryozoa_.

PORIFERA (Lat. _porus_, pore; and _fero_, I carry). Sometimes used to designate the _Foraminifera_, or the _Sponges_.

PRaeMOLARS (Lat. _proe_, before; _molares_, the grinders). The molar teeth of Mammals which succeed the molars of the milk-set of teeth. In man, the bicuspid teeth.

PROBOSCIDEA (Lat. _proboscis_, the snout). The order of Mammals comprising the Elephants.

PROCOELOUS (Gr. _pro_, before; _koilos_, hollow). Applied to vertebrae the bodies of which are hollow or concave in front.

PRODUCTA (Lat. _productus_, drawn out or extended). An extinct genus of Brachiopods, in which the sh.e.l.l is "eared," or has its lateral angles drawn out.

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 _pla.s.so_ 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 _zoon_, 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 cla.s.s 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.