NIAGARA FALLS AND VICINITY 263 



Glossary 



aberrant — differing from the type 



acanthopores — hollow spines occurring between the apertures, on the frond 



of a bryozoan 

 acinus — a berry 



adductor muscles — closing muscles in bivalve shells 

 agglutinate — firmly united 

 air-chambers — chambers below the living chamber in the shells of 



cephalopods 

 alar — pertaining to wings; the lateral primary septa of the tetracoralla 

 alate — having wing-like expansions 

 ambulacral areas — perforated areas in the test of an echinoderm, through 



which the tubed feet project 

 anastomosing — uniting to form a net work 

 angulated — with angles or corners 

 ankylosed — firmly united; grown together 

 annulations — rings, or ring-like segments 

 annulus — a ring; a segment of the thorax of a trilobite 

 antennae — paired articulated appendages of head of arthropod — trilobite 

 anterior — front 



aperture — opening of shells, cells, etc. 

 apex — terminal or first-formed portion of gastropod shells 

 apophysis — a calcareous process (in interior of shells, etc.) 

 appressed — pressed closely against 

 arcuate — arched; bent like a bow 



articulated — ^joined by interlocking processes, or by teeth and sockets 

 asperate — rough 



attenuated — tapering; or thinning 



auricle — ear, or anterior projection of the hinge of many pelecypods 

 auriculate — eared 



aviculoid — resembling Avicula, winged 

 axial canal — central canal of crinoid stem 



axial furrow^s — furrows or depressions delimiting the axis in trilobites 

 axis — central longitudinal division of the body of a trilobite 

 azygous — unpaired; the azygous side of the calyx of a crinoid has plates 



differing from those of the regular sides 



basals — lowest cycle or cycles (in forms with dicyclic base) of plates in the 



crinoidea 

 beak — area of the apex or initial point of a shell 

 biconvex — both valves convex, as in most brachiopods 

 bifid — split in two 

 bifoliate — two-leaved 

 bifurcating — dividing in two, forking 



