TERMINOLOGY. 



.Ipical pore. A pore at the proximal end of a corallite which 

 has been produced by budding. It communicates with the 

 cavity of the parent coralhte. 



Basal disk. The soft floor or basal part of the polyp, in the folds 

 of which all the radial skeletal structures are formed. 



Basal plate. The first secretion of calcium carbonate in the form 

 of an exceedingly thin plate. It can only occasionally be 

 seen in adult coralla. 



Calyx. The depression at the distal end of a corallite or solitary 

 corallum. 



Columella. A central longitudinal rod in the calyx or a knob 

 on the calicular floor. See Essential columella and Parietal 

 columella. 



Corallite. A single individual of a compound corallum. 



Corallum. An entire coral skeleton which may be solitary, 

 secreted by a single polyp, or compound and secreted by a 

 colony of polyps. 



Costcc. Ridges on the outside of the theca. They are opposite 

 to the septa and are covered by the epitheca when the latter 

 occurs. See Rugce. 



Dissepiments. Horizontal or sloping calcareous plates connect- 

 ing adjacent septa. 



Epitheca. A thin external calcareous deposit secreted by the 

 overlapping edge (the "edge zone") of the basal disk in a 

 single corallum. See Peritheca. 



Essential columella. A columella which develops independently 

 of other calicular structures or rarely as a specialization of 

 tabulae. See Tahellic. 



Eutheca. A wall formed by the introduction of new centers of 

 calcification between the outer ends of the septa. Accord- 

 ing to Vaughan, there is no systematic importance in the 

 distinction between eutheca and pseudotheca. It is doubtful 

 whether these terms will ever become useful in Paleontology, 

 as the centers of calcifi.cation are rarely to be seen in fossil 

 forms. Even the distinction between theca and epitheca is 

 obscure in many cases in Paleozoic corals. 



Major septa. The cycle of longer septa which reach nearly or 

 quite to the center of the calyx. 



