234 



TOILERS IN THE SEA. 



new mouth, and at length tentacles make their 

 appearance between the two mouths, each mouth 

 with its circlet of tentacles, and finally these are 

 resolved into two complete individuals, the one re- 

 taining the old mouth and stomach, the other the 

 new mouth and stomach. This is the mode of 

 increase which commonly prevails in the hemi- 



FIG. 49. THE ASTR^A (Astrcea pallida). 



spherical corals of the genus Astrcea (fig. 49), some 

 of which attain a diameter of from ten to fifteen feet. 

 A curious modification of this process takes place 

 in the Brain corals (Meandrind)^ in which the disk 

 enlarges indefinitely, a new mouth makes its appear- 

 ance, and then another, and another, until a string of 

 mouths appear in a line, before there is any separa- 

 tion or isolation of the new individuals ; this, how- 



