GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE VALLEY 363 



GLOSSARY OF TECHNICAL TERMS 

 acicular — needlelike 



aggrade — to build up to the condition of grade, as in a river 

 annulated — ringed, generally encircled by raised rings 

 annulations — raised rings 

 anterior — front 



aragonite — orthorhombic calcium carbonate, a common mineral 

 arcuate — arched 



arenaceous — of the texture of sand i. e. composed of visible sand grains 

 irrespective of chemical composition 



argillaceous — composed of or containing clay or hydrous silicate of alu- 

 minium 



arsenicopyrites or arsenopyrite — a mineral of a pale brass or almost silvery 

 color and in composition sulfld and arsenid of iron 



barytocelestite — the compound sulfate of barium and strontium, a com- 

 bination of the minerals barium and strontium 



beak — in pelecypod or brachiopod shells, the point of beginning of growth 

 of the valves 



bifurcating — dividing in two : forking 



bivalve — possessing two valves, as a pelecypod, a brachiopod or an ostracod 

 crustacean 



brachial valve — in the brachiopods, the valve which supports the brachidia 

 or arms ; it is generally the smaller of the two 



brachiopods — a class of marine invertebrates, with bivalve shells, the 

 valves symmetric about a median line drawn from beak to base of 

 each. A brachial and a pedicle valve are distinguishable 



breviconic — forming a short stout cone as in Gomphoceras 



bryozoan — a class of invertebrates building compound coral-like structures 

 either cylindric, with the cells radiating from a median axis, or leaf 

 or fernlike with cell openings, generally on one side only. The spread- 

 ing types often incrust seaweeds, shells or other objects 



calyx — the cup or living cavity in corals ; the " head " of crinoids 

 camerae — the air chambers in the cephalopod shell 

 cancellated — marked by two sets of intersecting ridges or grooves 

 carbonaceous — carbon or coal-bearing 



cardinal — appertaining to the region of the hinge in bivalve shells 

 cardioconehs — peloeypods of the type of structure of the cockle shell 



(Cardium) 

 carina or carination — an elevated ridge 

 celestine — see celestite 



celestite — the mineral form of sulfate of strontium 

 cephalon — head of Crustacea (trilobites) 



eephalopods — a class of marine mollusks typically with a shell straight, 

 curved or coiled, divided into chambers or camerae by partitions or 

 septa, which latter are pierced by holes drawn out into more or less 

 perfect tubes — the siphuncle 



cyrtoceracone — a cephalopod shell curved without coiling ns in Cyrtoeeraa 



