Glossary. 
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Plagloelase (Gr. plagios, slanting ; klastos, broken). A 
felspar with the planes of cleavage not at right angles 
to each other. 
Pleistocene (Gr. pleistos, most ; kainos, new). Often used 
as synonymous with “ Post-Pliocene.” 
Pliocene (Gr. pleion, more ; kainos , new). The later 
Tertiary period, in which recent or living species of mol- 
lusca were more numerous than the forms now extinct. 
Polype (Gr. polus , many ; pous, a foot). lies trie ted to the 
single individual of a simple Actinozoon, such as a 
sea anemone, or to the separate zooids of a compounded 
Actinozoon. Often applied indiscriminately to any of 
the Ccelenterata, or even to the Polyzoa. 
Polyzoa (Gr. polus , many ; and zoon, an animal). A 
division of the Molluscoida comprising compound 
animals, such as the Sea-mat, sometimes called Bryozoa. 
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. 
Pumice. A volcanic rock full of cavities formed by steam, 
commonly more nearly related to trachyte than to 
basalt. 
Pyrites (Gr. pur , fire). Sulphides of iron and copper. 
Quartz. The crystalline form of silica (oxide of silicon), 
Reptilia (Lat. repo , I crawl). The classes of the Verte- 
brata comprising the tortoises, snakes, lizards, 
crocodiles, &c. 
Rhynchonella (Gr. rhunchos , the nose or beak). A genus 
of Brachiopods. 
Sand dunes. Sand-drifts usually formed along the coast. 
