370 



Carina. — a projecting ridge running down the center of the 

 branches in some Fenestelloid and other Bryozoa ; the 

 projecting ridges on the septa of Heliophjlloni and other 

 corals. 



Cartilage — the compressible, elastic substance between the 

 hinge-margins of the valves of Pelecypods. The carti- 

 lage is the internal, the ligament the external, medium 

 for opening the valves. 



Cast — the impression taken from a mold. 



Cellnliferous — cell bearing. (Bryozoa commonlv have a 

 celluliferous and a non-celluliferous side.) 



Cephalic limb — the anterior border of the cephalon of a 

 Trilobite. 



Cephalon — the head-shield of Trilobites. 



Cheeks — the lateral portions of the cephalon of a Trilobite; 

 it is divided into fixed and free cheeks. 



Cheilyrimn — the triangular opening under the beak of the 

 brachial valve in those Brachiopods in which that valve 

 is furnished with a hinge area. 



Chilidium — the covering for the cheilyrium. 



Cicatrix — a scar. 



Cincture — a depression anterior to the beak in the shell of 

 some Pelecypoda. 



Cirri — root-like appendages to the stems of Crinoids. 



Clavicle — a heavy internal ridge running downward from 

 the beak in some Pelecypods. 



Columella — a central or axillary rod. 



Composite corallum — a compound corallum with coenen- 

 chyma or extrathecal calcareous tissue connecting 

 the corallites. (Ex. Galaxia and many other recent 

 forms.) 



Compound corallum — nmde up of corallites, either separate 

 or closely joined by their walls (Ex. Favosites). 



Concavo-convex — the shells of Brachiopods are normall}^ 

 concavo-convex, when the brachial valve is concave and 

 the pedicle valve convex ; reversed or resupinate, when 

 the reverse condition obtains. 



