4 io GLOSSARY. 



POLYPE (Gr. polus, many; pous, foot). Restricted to the single 

 individual of a simple Actinozoon, such as Sea-anemone, or 

 to the separate zooids of a compound Actinozoon. Often ap- 

 plied indiscriminately to any of the Ccelenterata, or even to 

 the Polyzoa. 



POLYPORA (Gr. polus, many; poros, a passage). A genus of 

 Lace-corals (Fenestellida.) 



POLYTHALAMOUS (Gr. polus] and thalamos, chamber). Having 

 many chambers; applied to the shells of Foraminifera and 

 Cephalopoda. 



POLYZOA (Gr. polus; and zob"n, animal). A division of the 

 Molluscoida comprising compound animals, such as the Sea- 

 mat sometimes called Bryozoa. 



PORIFERA (Lat. porus, a pore; and fero, I carry). Sometimes 

 used to designate the Foraminifera, or the Sponges. 



PR^MOLARS (Lat. pro:, before; molar es, 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 Mam- 

 mals comprising the Elephants. 



PROCCELOUS (Gr. pro, before; koilos, hollow). Applied to ver- 

 tebrae 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 Amer- 

 ica, 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 organized 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 soon, 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 exten- 

 sions of the body-substance which are put forth by the Rhizo- 

 poda 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. 



