mple _Actinozooen_, such as a Sea-anemone, or
to the separate zooids of a compound _Actinozooen_. Often applied
indiscriminately to any of the _Coelenterata_, or even to the
Polyzoa.

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

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

POLYZOA (Gr. _polus_; and _zooen_, 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 shell 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 _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 G