small bones composing the
digits of the higher _Vertebrata_. Normally each digit has three
phalanges.

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 partition; and _konos_, a cone).
The chambered portion of the internal shell 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 class 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 shells.

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 shells.

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

POLYPE (Gr. _polus_, many; _pous_, foot). Restricted to the single
individual of a si