AUSTRALIAN PORITES. 131 
The calicles appear as faint concave depressions in the otherwise smooth surface, without 
sharply defined contours, from 1-1'25 mm. in diameter. The walls, only slightly raised without 
median ridge, appear as a coarse, granular reticulum, in which, however, traces of a transverse 
and concentric symmetry of the elements can beseen. An irregular row of echinulate granules 
occupies the middle line, and on each side of these there are rows of thick, long septal granules 
which slope down, tapering rapidly into the calicle, These granules seem to be joined 
together by very fine threads. Below the surface these elements run together to form flakes. 
The septa consist chiefly of the large frosted or echinulate septal granules which, when longest, 
appear double, like a wall granule joined with a smaller septal granule, while within these 
septal granules are the pali, small and not conspicuous; only the four principals are of any 
size; the palic formula usually seems to be complete, B, fig. 3, p. 19. There is a columellar 
tubercle, large, echinulate, and ill-defined. The columellar tangle is obscured by the frosted 
granules, which seem to fill up the fossa. 
The section shows a very loose trabecular system. The colour of the unbleached coral 
is fawn. 
There are two colonies on the same mass, which is a crust of dead growths and foreign 
‘organisms. The two may have arisen by division of an earlier continuous colony. Encrust- 
ing explanate colonies, creeping irregularly over the substratum, frequently break up into 
patches. 
From one of these colonies there rises a rounded knob 2 cm. in diameter, while there is a 
detached excrescence 4 cm. high with a constricted neck 3 cm. thick. The knob is angular 
rather than rounded. 
a. Encrusting colonies. \ Zool. Dept. 97. 3. 9. 218 
b. A detached angular excrescence. 
121, Porites Great Barrier Reef (4928. (P. Queenslandice octava et vicesima.) 
(Pl. XVII. fig. 2; Pl. XXI. figs. 18, 19.) 
[Torres Strait, coll, A. C. Haddon ; British Museum. | 
Description.—The corallum is explanate and thin, and closely encrusting ; the edges 
bending sharply under for 1-2 em. and closely adhering. The upper surface is very wavy. 
These irregular encrusting colonies may form knobs and globular masses also with wavy 
surfaces. 
The calicles are conspicuous and deep, often 1:5 mm. in diameter. The walls surge up 
and have rounded tops of a light, ragged reticulum. The septa slope downwards and end in a 
rather large complete ring of eight small pali, which is, nevertheless, very inconspicuous. The 
large deep interseptal loculi are often gashed back rather far into the reticular wall, The 
columellar tubercle is deep down in the large open fossa, 
8 2 
