GARDINER—MADREPORARIAN CORALS. 265 
The collections contain a large number of young forms which I have carefully worked 
through, though in most cases I have not attempted to identify them. Such specimens 
can generally be referred to the Groups into which Déderlein has divided up the genus, 
but I have seldom found it possible from their morphology to refer them to any one 
species in their Group. Where one has only a single species of a Group from any locality, 
young species of the same Group may reasonably be referred to it, but when two or more 
species are available, identification is almost impossible. Young forms have naturally a 
tendency to resemble one another, and their coralla show as much or even more vegetative 
variation than those which are adult. New species consequently should never be founded 
on forms which are suspected of being immature. 
Further, the polyps of Fwngia have an extraordinary power of adaptability to their 
surroundings and of regeneration. The latter has already been referred to in connection 
with the Diaseris-group of Fungia, but I may add that in other Groups a considerable 
portion of the axial fossa must be present in any piece for the disc to be renewed. If a 
worm or small fragment of coral has settled on the disc, the tissues on either side are 
stimulated to grow up around it and perhaps even to enclose it. Again, if the animal 
is leaning up at an angle on the rock, one side of its dise may be strongly arched or even 
turned upwards, while the other side may be quite flat or turned downwards. If the 
animal is resting in a small hole in the reef rather below the general level of its surface, 
the corallum will be more or less arched in accordance both with the depth and breadth 
of the hollow, the main determining factor being the light necessary for the absorptive 
processes of the commensal algz of the polyp*. Again, the polyp may have settled in, 
or been swept into, some narrow hollow in the reef or between masses of corals or 
Lithothamnia. Under such circumstances it commonly attempts to keep its regular 
growth (which would give an approximately oval or round form in accordance with the 
species) by arching. When this is impossible, it will often grow out in an angular 
manner, or perhaps develop only the one half of its disc. Lastly, unfavourable food- 
conditions, particularly the absence or insufficiency of the light, tend to produce a 
lowering of the height of the septa and costze and of their teeth and spines. Few new 
septa arise at the edge of the disc, and all septa may appear thickened; the wall too (but 
of this I am not quite certain) tends to be less perforated. Apparently the energy of 
such forms is mainly directed to an increase of the breadth of their discs, little being 
left as it were for the elaboration of their costze and septa. 
Relatively few distorted and stunted specimens of /uwngia are found in collections. 
This is partially due to the immediate recognition and rejection of such by the individual 
collectors, but mainly to the fact that such forms occur in pits and hollows, which are 
narrow, crowded up with dead masses of the reef-rock, and perhaps little accessible. 
Further, they are generally of smaller size and tend to be overlooked. I have frequently 
found numerous dead specimens of such distorted or stunted forms on coral-beaches. 
Such specimens were common on the beaches of Hulule, Male Atoll, Maldives, and also 
* This does not apply to most of the species of the Cycloseris- and Diaseris-groups. hat 
SECOND SERIES.—ZOOLOGY, VOL. XII. 37 
