218 
Mr Gardiner, On the Rate of Growth 
imagined as flat plates, covering the same horizontal areas, as 
the specimens themselves naturally covered when alive. 
Name of Coral 
Time of 
Growth 
in Days 
First 
Weight 
in 
Grams 
Present 
Weight 
in 
Grams 
Weight 
in 
Water 
in 
Grams 
Specific 
Gravity 
Volume 
in c.c. 
Thick- 
ness as 
a Sheet 
in mm. 
1 . Stylophora 
raristella, var. 
wilsoni 
1030 
310 
293 
104 
1-55 
189 
14-1 
2. Stylophora 
raristella, var. 
wilsoni 
1030 
186 
168 
53 
1-46 
115 
12-8 
3. Pocillopora 
suffruticosa 
1030 
194 
190 
106 
2'26 
84 
12*2 
4. Pocillopora 
suffruticosa 
1030 
131 
127 
71 
2*27 
56 
10-2 
5. Pocillopora 
plicata, var. 
aspera 
1030 
195 
177 
57 
1 47 
121 
24*7 
In examining the table, the difference between the specific 
gravities and volumes of the two species of Pocillopora is most 
noticeable. Assuming that the corallum is an excretion, it 
would naturally be supposed that the greater the surface the 
quicker the rate of growth. Yet the reverse here is the case, 
P. plicata being a fairly massive species, while P. suffruticosa 
branches into fine twigs. It is not known, however, when the 
larvae affixed themselves, and the real time of growth is pro- 
bably in every case very much less than the recorded time. 
For comparison the last column is the most important, but 
it assumes that the position of growth, the vertical and hori- 
zontal axes, are known. It is necessary hence that these should 
be marked (by paint, or some other means), when the specimens 
are obtained. This is more especially the case with massive 
than branching species. All true reef corals grow towards the 
light, and with branching specimens of any size, remembering 
that the ends of the central larger branches will be approxi- 
mately vertical and that the underside has only short blunt 
