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NEW YORK STATE MUSEUM 



octahedron — crystal form with eight equal faces, each an equilateral tri- 

 angle 



old land — that portion of land behind the coastal plain which supplied the 



material of which the strata of the coastal plains were formed 

 orthid — resembling or related to the brachiopod Orthis 

 orthoceracone — a straight conelike shell like that of Orthoceras 

 orthoceratites — belonging or related to the genus Orthoceras 

 outcrop — intersection of rock mass with the surface 



outlier — erosion remnant left in a valley at a distance from the plateau 



or upland with which it was previously continuous 

 ostracods — a group of marine Crustacea generally minute, inclosed in a 



bivalve shell which does not show concentric lines of growth 

 overlap — extending beyond an underlying stratum 



pedicle valve — that valve, generally the larger, of the brachiopod shell 

 which gives emission to the pedicle or supporting organ. This valve 

 also contains the teeth by which the hinging of the valves is accom- 

 plished 



pelecypods — the class of bivalve mollusk or ianiellibranchs to which the 

 clam belongs 



peneplain — the nearly level surface, almost a plain, resulting from the 

 erosion of an uplifted region by subaerial agents, to a condition 

 approaching sea level 



pentameroid — related to the genus Pentamerus among the brachiopods 



periphery — the margin of the circumference 



pervious — penetrable by water 



petalite — a complex silicate of aluminum with sodium, potassium or lith- 

 ium 



plications — folds or flutings 



posterior — pertaining to the hinder end 



prenuncial — announcing beforehand, heralding the coming of 

 protuberant — projecting outwards 



pteropods — a class of marine mollusks floating on the surface of the water 

 and having delicate generally transparent shells, needlelike in the 

 commonest forms 



punctate — marked by spots or shallow pits 



pustules — small elevations or tubercles 



pustulose — covered with pustules 



pygidium — the posterior portion of the body of the trilobite, erroneously 

 called tail 



pyrite — the mineral form of bisulfid of iron F e S 2 

 pyritiferous — containing or bearing pyrite 



pyritohedron — the pentagonal dodecahedron (which see) a form commonly 

 assumed by pyrite crystals 



quartz — the mineral form of oxid of silicon (Si0 2 ) 



quartzite — a rock resulting through the metamorphic change of a quartz 

 sandstone, the quartz grains become closely united by a paste or 

 matrix of quartz 



radii — radiating lines, such as are found on the surfaces of many shells 

 revived stream— streams resuming activity owing to elevation or other 

 causes 



