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. cellulosa 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. 



