CHAPTER IV. 



Glossary of Paljeontological Terms. 



Aberrant — differing from the type. 



Acanthopores — hollow spines occurring between the aper- 

 tures, on the frond of a Bryozoan. 

 Adductor muscles — the closing- muscles in bivalve shells. 

 Agglutinate — firmly united. 

 Air-chambers— the 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 — the perforated areas in the test of an 



Echinoderm, through which the tubed feet project. 

 Anastomosing — uniting so as to form a net work. 

 Anchylosed — firmly united; grown together. 

 Annulus — a ring: a segment of the thorax of a Trilobite. 

 Anterior — front. 



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. 

 Auricle — the ear, or anterior projection of the hinge of many 



Pelecypods. 

 Auriculate — eared. 

 Azygous — unpaired; the azygous side of the calyx of ;i 



erinoid 1ms plates differing from those of the regular 



sides. 

 Axial furrows — the furrows or depressions delimiting the 



;ixis in Trilobites. 

 Axis— the central longitudinal division of the body of a 



Trilobite. 



