OF POLYPS. 147 



encircling the disk. Coral mural, septal and endothecal ; 

 growth vertical and centrifugal, producing turbinated 

 forms which are often elongated. 



Families, Litliopliyllidce, Mceandrinidce, JEusmillidce, 

 CaryophyllidcV) Sti/linidce, Astreince, Oculinidce, Stylo- 

 phoridod. 



SUBORDER IY. MADREPORACEA (Madreporariaperforata). 



Tentacles in definite numbers, twelve or more, well de- 

 veloped, encircling the narrowed disk, therefore nearer the 

 mouth ; polyps with the upper portion much exsert, flexile; 

 growth chiefly vertical ; coral mural and septal, porous. 

 Polyps compound by budding, sometimes simple. 



Families, Eupsammidca, GemmiporidcE, Poritidce, Mad- 

 reporidw. 



ORDER II. ACTINARIA. 



Polyps with well developed, often highly specialized, 

 basal or abactinal region. Walls well developed, tenta- 

 cles longer, more concentrated around the mouth, which 

 is also, usually, if not always, furnished with special tenta- 

 cular lobes or folds. Ambulacral spaces always open, 

 destitute of connecting tissues and solid deposits. 



SUBORDER I. ZOANTHACEA. 



Polyps encrusting, adherent, budding from mural expan- 

 sions ; tentacles simple, short, at edge of disk. 

 Fam i 1 i e s , Zoan thidce, Bergidoi . 



SUBORDER II. ANTIPATHACEA. 



Polyps connected by a coenenchyma, secreting a solid 

 sclerobase or coral axis. Tentacles few, six to twenty- 



