GLOSSARY. 301 
PLEUROTOMARIA (Gr. pleura, the side; tomé, 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. 
PotypaRy. The hard chitinous covering secreted by many of the Hydrozoa. 
POLYPE (Gr. polus, many ; pous, foot). Restricted to the single individual of 
a simple Actinozoén, such as a Sea-anemone, or to the separate zooids of a 
compound Actinozoén. Otten applied indiscriminately to any of the Celen- 
terata, or even to the Polyzoa. 
PoLypora (Gr. polus, many; poros, a passage). A genus of Lace-corals 
(Fenestellide). 
POLYTHALAMOUS (Gr, polus ; and thalamos, chamber). Having many chambers ; 
applied to the shells of Foraminifera and Cephalopoda. 
PoLyZOA (Gr. polus; and zoén, animal). A division of the Molluscoida com- 
prising compound animals, such as the Sea-mat—sometimies called Bryozoa. 
PORIFERA (Lat. porus, a pore ; and fero, I carry). Sometimes used to desig- 
nate the Foraminifera, or the Sponges. 
PRAMOLARS (Lat. pre, 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. ; 
PROCELOUS (Gr. pro, before ; koilos, hollow). Applied to vertebre the bodies 
of which are hollow or concave in front. 
Propucta (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 im- 
pressions 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 or- 
ganised 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 zodén, animal). The lowest division of the animal 
kingdom. 
PSAMMODUS (Gr. psamimos, sand ; odous, tooth). An extinct genus of Cestra- 
ciont Sharks. 
PSEUDOPODIA (Gr. pseudos, falsity; and pous, foot). The extensions of the 
body-substance which are put forth by the hizopoda at will, and which 
serve for locomotion and prehension. 
PSILOPHYTON (Gr. psilos, bare ; phuton, plant). An extinct genus of Lyco- 
podiaceous plants. 
PTERANODON (Gr. pteron, Wing ; a, without; odous, tooth). A genus of Ptero- 
saurian Reptiles. 
PTERASPIS (Gr. pteron, wing; aspis, shield). A genus of Ganoid Fishes. 
PTERICHTHYS (Gr. pteron, wing ; tchthus, fish). A genus of Ganoid Fishes. 
PTERODACTYLUS (Gr. pleron, wing; daktulos, finger). A genus of Pterosaurian 
Reptiles. 
Bet ee (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. 
PrinopicTya (Gr. ptilon, a feather ; diktuon, a net). An extinct genus of 
Polyzoa. 
