258 MADREPORARIA. 
Taste II].—A SURVEY OF THE DISTRIBUTION OF THE DEFINABLE 
GROWTH-FORMS. 
[N.B.—References to the figures illustrating the specimens mentioned in the following lists will be 
found in Table I.} 
As in the corresponding Table in Vol. IV., p. 169, we again assume that the form of the 
initial colony of Porites was a small plano-convex disc, and that from it all subsequent growth- 
forms start. We may add, also, that the introductory remarks there made are equally applicable 
to this genus also. A brief discussion on the taxonomic value of the growth-form in so 
variable an organism as a coral colony will be found in the observations at the end of this Table. 
A. Plano-convex. 
This ideal primitive form does not seem to persist as a growth-form, at least without 
considerable modification, in Porites. In the more rigid Goniopora it occurs somewhat 
frequently, see Vol. IV. I have, however, put under this heading all those forms with 
expanding creeping edges and with gradual thickening of the central regions, which central 
regions remain more or less smoothly convex. However high these centres grow there is 
always this difference between such stocks and the globular form, inasmuch as the central 
region of the latter rises rapidly and swells so as to overhang the edges, which early cease to 
show any lateral growth. 
P. Tonga Islands 3. Creeping irregularly over dead coral. 
P. Fiji Islands 20. Rises into a steep mound. 
P. Laysan 2. Convex, but with uneven surface. 
P. Bay of Panama 1. With very irregular marginal outline. 
P. Great Barrier Reef 22. Centre rises rather steeply to a mound. 
P. Ceylon 10 and 11, On the shell of the pearl oyster. 
P. Diego Garcia 1. With edges closely adherent, even bending under. 
P. Egypt 1. Expanded, convex. 
Doubtful :-— 
P. Ellice Islands 15. 
P. Great Barrier Reef 32. 
P. Solomon Islands 2. A fragment. 
Perhaps young stages of globular forms. 
B. Luplanate. 
These forms arise from primitive plano-convex colonies by early cessation of growth in 
thickness with rapid extension of the margin, the budding being confined to the polyps round 
the edges of the epitheca. They may be :— 
a, Purely encrusting, that is, without free edges. 
b. With free edges. 
