DISTRIBUTION OF GROWTH-FORMS. 261 
P. North Australia 6. With knobs and submoniliform branches. 
P. North-West Australia 6. . 
P. North-West Australia 8. Occurs with an older form belonging to next group b. 
P. Java Sea 2. Long spikes, rising from explanate base, and often branching. 
P. Philippines 4. Urregularly tuberous. 
P. Singapore 5. Tall columns, flattened and spatulate at the tips. 
P. Mauritius 4. Tall columns, rounded, and slightly moniliform. 
P. Ceylon 12. Mammille. j 
b. Cluster formations without expanding bases. These may either be older stocks of the 
last section, a, or new growths. New growth periods of will mostly start from the tops of 
their first-formed clusters, and, beginning to envelop them, will have their centres already raised 
for the formation of more towering clusters, from which, in some cases at least, the explanate 
basal portions will droop downwards. The resulting stocks are large clusters swelling out 
above irregular stalks, round which creeping edges depend. But the same result would also be 
obtained if such a colony started not from a previous growth but from a raised point of an 
inorganic substratum. As arule in cluster-formations the remains of earlier smaller clusters can 
be traced in fractures through the base. In P. Great Barrier Reef 24, the whole process can 
be traced in a single specimen. It began as an encrusting colony with mammillate centre. 
The explanate encrusting layer increased up to a certain size, but with a comparatively 
much larger central cluster after each growth period. The living layer ultimately merely 
swelled the cluster, no longer even reaching down to the old explanate pedestal of the 
stock. This phenomenon is sometimes seen by comparing specimens of the same coral at 
different ages, e.g. in P. Great Barrier Reef 6 and 26. In such cases, where two specimens 
show the two stages, the younger stages are mentioned under C, a, and the other in the list 
now following. 
P. Ellice Islands 3. The specimens show traces of—(1) a smooth explanate stage ; 
(2) a mound of round lobes ; (3) a mulberry shape ; and lastly (4) a tall conical 
mass of similar lobes. 
_ Solomon Islands 4. A tangle of thin ccenenchymatous processes. 
_ Caroline Islands 4. A very irregular mulberry-shaped mass. 
_ Great Barrier Reef 15. A swelling mass of irregular tuberosities. 
Great Barrier Reef 17, & cluster of irregular mammille or digitform processes. 
Great Barrier Reef 24. Shows the process described in the note above. 
. Great Barrier Reef 26. Large dense cluster of stout lobes. A younger stage 
mentioned in list C, a. 
. Great Barrier Reef 41. Cluster of small ridges, which divide up irregularly. 
. Great Barrier Reef 42. Small clusters of mammille, which radiate outwards in 
all directions from centres. 
- North-West Australia 2, A mound of short thick irregular knobs. 
. North-West Australia 6. Trregular lobate ridges. 
. Singapore 3. Rises into tall clusters of processes, often flat columns with dividing 
tops. 
P. Singapore 4. A cluster of very short knobs from which thin digitform processes 
rise, the cluster apparently branching. 
P. Ceylon 13. A small mulberry-shaped mass. 
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