124 Mr. J . E. Gray^s Outlme of an Arrangement of Stony Corals. 



these animals each individual is distinctly divided^ and hence each 

 cell has distinct parietes ; but on the contrary in the Porites the 

 separate animals do not secrete any calcareous matter between 

 themselves^ hence there are no distinct cells on the surface of the 

 coral, and the coral is very porous, being pierced in every direc- 

 tion, and what are laminae in other corals in this genus are only 

 calcareous spicula. 



The animals of the stony corals, besides being reproduced by 

 eggs, which are developed between the septa of the stomach and 

 emitted by the mouth, as in soft coralless Actinice or the coria- 

 ceous Zoanthi, and form new individuals or masses, also have the 

 power of developing buds from their sides, or of increasing them- 

 selves by the spontaneous division of their stomachs, and it is by 

 these means that the masses of coral are enlarged and continued; 

 and the forms which the various kinds of coral assume in their 

 growth, which gives the most prominent differences between their 

 genera, depend on the manner in which these buds are developed, 

 or the body of the animal spontaneously divided, each cell or 

 branch being either the growth of a separate bud or resulting 

 from this spontaneous division. 



, Before the spontaneous division of the animals takes place, the 

 stomach enlarges and a new mouth opens near the original one in 

 the disc, and from the mouth new radiating lamellse arrange 

 themselves, forming new centres, and this process is again and 

 again repeated. Now as the laminae of the coral represent the 

 plates in the stomachs, and the centre of the plates the mouth, 

 this kind of development may be observed in the coral nearly as 

 well as if the animal was present. 



The effect of this kind of spontaneous division on coral is very 

 different in the two forms which the animals assume during their 

 growth; and as these forms gradually pass into each other, so 

 their peculiarities become less apparent. If the animal grows in 

 height, raising itself on the gradually solidified part of the former 

 coral, as in the branched Caryophyllia fastigiata, Lam., where 

 the cells are round, they at length become oblong, then separate 

 in the middle, the separation becomes more complete, and at 

 length two complete similar cells are formed*, each placed on 

 the end of a branch divided by a fork, and this process is repeated, 

 forming a forked coral. The same kind of separation takes place 

 in Caryophyllia sinuosa, Lam., but here the divided portions some- 

 times form separate stars, and at others only form new centres 

 in the enlarged old star, which remains surrounded by the same 

 edge. It is this latter kind of division which forms the elon- 

 gated compressed cells of the Meandrince and the sinuous con- 



* See Synopsis Brit. Mus. 1842, 130. 



