s of Dicynodont
Reptiles.

OVIBUS (Lat. _ovis_, sheep; _bos_, ox). The genus comprising the
Musk-ox.

PACHYDERMATA (Gr. _pachus_, thick; _derma_, skin). An old Mammalian
order constituted by Cuvier for the reception of the Rhinoceros,
Hippopotamus, Elephant, &c.

PALAEASTER (Gr. _palaios_, ancient; _aster_, star). An extinct
genus of Star-fishes.

PALAEOCARIS (Gr. _palaios_, ancient; _karis_, shrimp). An extinct
genus of Decapod Crustaceans.

PALAEOLITHIC (Gr. _palaios_, ancient; _lithos_, stone). Applied
to the rude stone implements of the earliest known races of men,
to the men who made these implements, or to the period at which
they were made.

PALAEONTOLOGY (Gr. _palaios_, ancient; and _logos_, discourse).
The science of fossil remains or of extinct organised beings.

PALAEOPHIS (Gr. _palaios_, ancient; _ophis_, serpent). An extinct
genus of Snakes.

PALAEOSAURUS (Gr. _palaios_, ancient; _saura_, lizard). A genus
of Thecodont Reptiles.

PALAEOTHERIDAE. (Gr. _palaios_, ancient; _ther_, beast). A group
of Tertiary Ungulates.

PALAEOZOIC (Gr. _palaios_, ancient; and _zoe_, life). Applied to
the oldest of the great geological epochs.

PARADOXIDES (Lat. _paradoxus_, marvellous). A genus of Trilobites.

PATAGIUM (Lat. the border of a dress). Applied to the expansion
of the integument by which Bats, Flying Squirrels, and other
animals support themselves in the air.

PECOPTERIS (Gr. _peko_, I comb; _pteris_, a fern). An extinct
genus of Ferns.

PECTEN (Lat. a comb). The genus of Bivalve Molluscs comprising
the Scallops.

PECTORAL (Lat. _pectus_, chest). Connected with, or placed upon,
the chest.

PENTACRINUS (Gr. _penta_, five; _krinon_, lily). A genus of Crinoids
in which the column is five-sided.

PENTAMERUS (Gr. _penta_, five; _meros_, part). An extinct genus
of Brachiopods.

PENTREMITES (Gr. _penta_, five; _trema_, aperture). A genus of
_Blastoidea_, so named in allusion to the apertures at the summit
of the calyx.

PERENNIBRANCHIATA (Lat. _perennis_, perpetual; Gr. _bragchia_,
gill). Applied to those Amphibia in which the gills are permanently
retained throughout life.

PERISSODACTYLA (Gr. _perissos_, uneven; _daktulos_, finger).
Applied to those Hoofed Quadrupeds (_Ungulata_) in which the feet
have an uneven number of toes.

PETALOID. Shaped like the petal of a flower.

PHACOPS (Gr. _phake_, a lentil; _ops_, the eye). A genus of
Trilobites.

PHALANGES (Gr. _phalanx_, a row). The