GEOLOGY AND PALEONTOLOGY OP THE SCHOHARIE VALLEY 363 



GLOSSARY OF TECHNICAL TERMS 



acicular — iieedlelike 



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 sulfid and arsenid of iron 



tarytocelestite — 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^ — sl 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 ca^aty in corals ; the " head " of crinoids 



oamerae — 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 



cardioconchs — pelecypods 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) 

 <?ephalopods — 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 as in Cyrtoceras 



