CORALS AND CORAL MAKERS. 39 



or crowded clusters of such stems branching variously and 

 having each branch surmounted with its one polyp (figure j). 

 32) ; or, if there is lateral growth and but little of upward, it 

 produces leaf-like forms and graceful groups or clusters of 

 leaves, vases, and other shapes ; or, if the germ-polyp is capa- 

 ble of lateral growth alone, the results are simple lines of 

 polyps creeping over the supporting rock, like the creeping 

 stolons of a plant, or else encrusting plates, spreading outward 

 like a lichen. 



In the descriptions of corals the following terms have the significations 

 annexed. Those aheady mentioned are here repeated to bring them all 

 together. 



Zo'dthotne. — The compound animal mass produced by budding. 



Corallum: — The coral either of the compound mass, or of the solitary 

 polyp. 



Corallet (in Latin, corallulum). — The- coral of a single polyp in a com- 

 pound corallum. 



Calide. — The polyp cell in the top of a corallet, or of a solitary coral- 

 lum, within the walls of the cells ; it is sometimes flat at top, that is, 

 without the usual depression. 



Septa. — The radiated plates of the cell or calicle. 



Dissepiments.— '^xcidXX cross plates between adjoining septa (sometimes 

 wanting). 



Synapticulce. — Minute cross bars uniting the surfaces of adjoining septa. 



Ccenenchyma. — The common mass of the corallum between its differ- 

 ent polyp cells or corallets, as in the Madreporae, Gemmiporae and Den- 

 drophyllioe. 



Epitheca. — The coral layer sometimes deposited over the exterior of the 

 corallum during the life of the polyp by the outer skin before it dries away, 

 as explained on page 25. 



Peritheca. — The epitheca of a compound group or zoothome (fig. p. 50). 



Exotheca. — The portion of the corallum outside of the walls of cells in 

 many coralla of the Astraea family, and some others, in which the polyps 

 of the mass ai;e properly in contact, and there is consequently no true 

 ccenenchyma. 



Endotheca. — The portion of the corallum inside of the walls of the cell. 



We may now state briefly the characteristics of the grander 

 divisions of the Actinoid polyps, several of which have been 

 illustrated in the preceding figures. 



The tribes adopted are those recognized by Prof Verrill, 

 and have the limits he has assigned to them. The classification 



