216 
Mr Gardiner , On the Rate of Growth 
barrier reefs of similar form in the same islands. The bottom 
of the lagoon is hard sand or rock, little or no mud. As the 
buoy slowly rises and falls with the tide, the depth of any part of 
the chain is constant. The current is purely tidal, varying little 
during the year; it is never of sufficient force to cause the 
buoys to drag in any way. The harbour is very largely protected 
by the high island from the wind ; outside the reef is broad, and 
there is not sufficient sea-room for rollers of any size to come 
up. Wind hence, except during hurricanes — and none such oc- 
curred during the growth of the specimens under consideration 
— is a negligible quantity. The depth of the lagoon, where the 
buoys are situated, is about 6 fathoms, so that the specimens 
were both well above any movement of sand or mud on the bottom 
and below any mere surface disturbance. 
Considering that the tidal currents cause an ample change in 
the waters of the lagoon, and are almost continuously though not 
very appreciably felt in the harbour, together with the other con- 
ditions above described, I can only come to the conclusion that 
the situation of the specimens was one peculiarly favourable to 
a very vigorous and rapid growth. The same deduction would 
further seem to me amply justified alone by the numerous branch- 
ings and small size of the twigs of all the specimens, as well as the 
lightness of their different coralla. 
The five specimens belong to the genera Stylophora and 
Pocillopora, both groups of extremely vigorous growth and general 
distribution throughout the Indian and Pacific Oceans. In Fiji 
they grow on the outer slopes, reef-flats and in the lagoons of 
probably every reef in the whole group. Their abundance is so 
great that, with the exception perhaps of Madrepora alone, no 
single coral genus can claim an equal importance with either in 
building up the reef limestone, with the ultimate fate of which 
I am not here concerned. 
Two of the specimens I refer to Stylophora raristella (De- 
france) 1 , a fossil species from the miocene of Turin. The forms 
known as S. danae Ed. & H., S. cellidosa Quelch, and several 
others are probably only varieties of this species (if the descrip- 
tions of the latter are accurate), but the group of which it is 
the representative would appear probably to be quite distinct 
from the forms, of which S. digitata (Pallas) is the central species. 
The specimens of Stylophora in this country are not sufficiently 
numerous to examine the species question in the genus, nor have 
they been collected with this view. I cannot regard the differ- 
ences in my specimens as more than varietal, and, as they differ 
from any of the so-called living species, I propose to give them the 
1 For references see “ Histoire des Coralliaires ” par Mm. H. Milne Edwardes et 
J. Haime, tome n. p. 138, 1857. 
