369 



Basals — the lowest cycle or cycles (in forms with dicyclic 

 base) of plates in the Crinoidea. 



Beak — the area of the apex or initial point of a shell. 



Biconvex — both valves convex, as in most Brachiopods. 



Bifid — split in two. 



Bifurcating — dividing in two, — forking. 



Biserial — with double series or rows. 



Brachial — pertaining to the brachia or arms of Brachi- 

 opods or Crinoids ; one of the arm plates of Crinoids. 



Brachidium — the calcareous support of the arms in Brachi- 

 opods. 



Branchiae — gills. 



Bryozoum — the whole compound colony of the Bryozoa. 



Bulbiform — bulb-shaped. 



Byssal notch — the notch or opening for the emission of the 

 byssns (supporting-threads spun by the foot) in the 

 Pelecypoda. 



Callus — the thickened portion of the inner lip of Gastropods, 



which usually covers portions of the preceding volutions. 

 Calyx — (1) the cup of corals, limited below by the septa; 



(2) the body, exclusive of the arms, of Crinoids, Cystoids, 



and Blastoids. 

 Carapace — the hard shield or shell of Crustacea. 

 Cardinal — pertaining to the area of the beak in Brachiopods 



and Pelecypods. 

 Cardinal process — the process from under the beak of the 



brachial valve of Brachiopods, to which the diductor 



(opening) muscles are attached. 

 Cardinal quadrants — the two quadrants of a Tetracorallum 



which bound the main, or cardinal, septum. 

 Cardinal septum — the first or main of the four primary 



septa of a Tetracorallum; the cardinal septum has the 



pinnate arrangement of the secondary septa on both 



sides. 

 Cardinal teeth— the teeth under the beak in the Pelecypods; 



the teeth in the pedicle valve of the Brachiopods. 



