DISTRIBUTION OF GROWTH-FORMS. 263 
Doubtful :— 
P. New Guinea 1. Large masses of stout cylindrical branches. 
P. Sandwich Islands 4. Consists of uneven, angular, and crowded branches. 
Forms with roughened surface, very suggestive of the true ccenenchymatous Porites, are 
produced by excessive crowding of the calicles. Small groups rise up into rough, wart-like 
eminences—e.g., P. Fiji Islands 24, P. China Sea 13, P. Mauritius 5; in the last case even 
leading to nodulated branches. All such must be distinguished from true ccenenchymatous 
forms, which are not due to any overcrowding, but on the contrary to a scattering of the 
calicles, with a large amount of intervening tissue. 
E. Massive and Glomerate. 
These forms are to be regarded as due to the growth of the initial plano-convex colony 
more rapidly in the central regions than round the edges. It is obvious that, according to the 
relative rapidity of growth of the two, we may get—(1) thick flat cakes ; (2) globes ; (3) tall 
ovals and columns (the expanding sheaf formation) ; and (4) thin stems, which are the starting- 
point for branching and dendriform stocks. 
In nature, of course, this ideal series is much interfered with by all the chance variations 
of the environment, and it is often difficult to attribute individual specimens to any definite 
kind of growth, especially as the same shape of stock may in some cases be attained, as it 
were, accidentally along different lines of growth. 
a, Thick expanding cakes :— 
(i.) With nearly perpendicular, or only slightly bulging sides. 
P. Great Barrier Reef 7. A boring sponge may have influenced this growth. 
P. Great Barrier Reef 30, With level top and lobate outline. 
P. Cape of Good Hope 1. Smooth top, but very irregular outline. 
(ii.) With sides, where growth is rapid, projecting far over the substratum, but with 
flat, wavy top. Cf. the diagram PI. XIII. fig. 8. 
P. Fiji Islands 4. With roughened top surface. 
P. Fiji Islands 7. Thick, with rounded edge. 
P. Fiji Islands 22. With very smooth edge ; here sharp, there rounded. 
P. Ellice Islands 5. Thin, with sharp edge. 
P. Ellice Islands 6. Edge sharp and wavy. 
P. Ellice Islands 8. May also belong to E, ?. 
P. Ellice Islands 9. A complete stock ; sides here steep, there sharply projecting. 
P. Ellice Islands 10 ? 
This (ii) seems to be a definite type of growth-form, and may be compared to an 
expanding sheaf formation, in which the centre ceases to grow, and only the lateral parts, 
which bend outwards all round, continue the growth of the coral. 
b. Globular forms :— 
(i.) With smooth, or only slightly indented surface, continuing to grow, unless 
accidentally distorted, as single rounded stocks. 
P. Tonga Islands 7, A quarter of a globe, with slightly wavy surface. 
P. Ellice Islands 7. Fragment, with smooth surface, as if chipped off a rounded mass. 
