ZOANTHAKIA. 



163 



nally it presents the figure of an irregular trellis-work, more or less 

 loosely connected in its meshes. As a type of this organization, we 

 give a figure of the Forked Porites (P. furcata, Fig. 78), of the 

 natural size. The branches are generally dichotomous, that is, rising 

 in pairs obtusely lobed. In some of the species the rays are more 

 fully marked, and resemble a bed of miniature anemones thickly 

 crowded together, as in Gonispora columna, in which the polypi 



Fig. 18. Porites furcata (Lamarck), natural size. 



have a central mouth, round which the twelve short tentacula radiate ; 

 the coral is stony, fixed, branched, or lobed, having a free surface 

 covered with a great number of regular stars, which are highly 

 characteristic, and cannot be confounded with those of an astrea or 

 madrepore. 



In the Tabulate Madreporides, the polyp is essentially composed 

 of a highly-developed mural system. The visceral chambers are 



M 2 



