INTRODUCTION. 5 
‘The base, sides, calice, calicular edge or margin, are self-explanative terms. The 
terms calicular fossa, and interseptal loculi, have been noticed. 
These are the usual structures observed, and they are modified m every way to 
produce the various shapes of corals. 
The word corallum is used to individual corals when solitary in their growth; but 
when aggregated to form a compound mass each individual of the mass is called a 
corallite, the aggregation retaining the name of coral/um. 
The corallites of a compound corallum may be united together by the fusion of their 
walls, no coste existing, or they may be united by a great development of the coste and 
the exothecal dissepiments. Sometimes the exotheca is so developed as to form a very 
distinct tissue between the corallites; it is then mere or less cellular, and is termed 
cenenchyma and peritheca. 
Some simple and many compound corals extend by a process of lateral calicular 
growth, so that there is not a circular or ovoid calice, but a long, and often gyrate assem- 
blage of septa; such a calice is called “serial.” 'The shape of compound corals is deter- 
mined, to a great extent, by their method of yemmation,’ and by the»existence of 
Jissiparous* and serial® calices. 
II.—ANATOMY OF THE SCLERENCHYMATOUS STRUCTURES. 
Calice, Wail, Septa, Pali, Columella, Coste, Endotheca, Exotheca, Hpitheca, Peritheca, 
Ceenenchyma. 
Calice.—The upper and open extremity of a corallum is called its calice.* Its outline 
is formed by the upper or marginal part of the wadl, and is very various in its form. The 
superior boundary is determined by the greater or less exsertness of the septa, and its 
depth by the greater or less prominence of the structures forming the floor of the 
Jossa. 
The periphery of the calice is called its margin, and its floor is formed by the septa, 
the interloculi, the top of the columella, and, when that structure does not exist, by the 
axial space. 
Every variety of form may be noticed in the outlines of calices ; they may be circular, 
circular and slightly compressed, oval, elliptical, elliptical and slightly angular at the end 
of the long axis, ovoid and compressed from side to side, ovoid at one end, linear or leaf- 
1 Plate III, fig. 15 ; Plate IV, figs. 10, 11, 17, 18. 
2 Plate IV, figs. 12, 13. 3 Plate IV, figs. 14, 15. 
* Plate I, figs. 1, 11,6; Plate II, figs. 11, 13, 14; Plate III, figs. 15, 17, 18, 19, 20; Plate IV, figs. 
8, 11, 12. . 
