
No. 426.] MADREPORARIAN CORALS. 465 
flatten out by this extremity their walls will be in close con- 
tact, and a colony of three young polyps will result. 
Such a colony, adherent to a pebble, and formed of seven 
individuals, is represented in Fig. 2. The drawing was made 
two or three days after fixation of the larva, when the adult 
polypal form was beginning to be assumed, and the tentacles 
were just appearing as rounded prominences. All the polyps 
are at practically the same stage of development, proving that 
they settled synchronously, or nearly so. They are irregularly 
arranged with regard to one another, and in their effort to fully 

expand the walls press upon one another, and produce distortion 
of the proximal part of the column. 
To the under surface of another small pebble thirty-eight 
larvae attached themselves in groups of two, three, or more. 
One of these groups contained a dozen or so young polyps, all 
touching, the mutual pressure producing an angulation of the 
normally circular base. Another group of thirty-two became 
adherent during a single night to the surface of a small glass 
dish. In this case nearly all the members, upon flattening, 
were touching to a greater or less degree. 
Fixation having taken place, the larva, now to be regarded 
as polyps, seemed remarkably vigorous, and underwent the 
next stages of development with comparative rapidity. In 
