﻿56 • MADREPOEARIA. 



d. Tongatabu. J. J. Lister, Esq. 97. 6. 18. 18. 



Like the last but more convex, being cap-shaped. Under the cap, two corroded previous 

 growths are traceable. The edge of the new growth tends to turn outwards horizontally. 



e. Tongatabu. J. J. Lister, Esq. 97. 6. 18. 19. 



A thick massive block with traces of five successive encrusting growths. The ramparts 

 are here and there broken up into curved plates bordering the calicles. In a specimen from 

 Eotuma Island, in the Cambridge University Museum, the same character is seen, groups of 

 such calicles rising up into slight protuberances. " 



86. 12. 9. 360. 

 f,g. Kandavu. H.M.S. 'Challenger, q^) iq i/? -,yj 



These two specimens are small massive fragments with the calicles smaller than they are 

 in the foregoing. 



40. Montipora socialis. (PI. V. fig. 4.) 



Description. — Corallum massive and encrusting, without or with expanding edges, 

 • 5 cm. thick, when free supported by epitheca. 



Calicles very conspicuous as deep round holes, less than 1 mm. diameter. The septa are 

 short, thick, and regular, as continuous toothed ridges, twelve in number and nearly equally 

 developed ; the primaries are, however, distinguishable. One slightly thicker directive ; fossa 

 very deep and open. On the under side, between the edge and the epitheca, a very few small 

 calicles as round deep holes. The margin of the calicles distinct in the bases of the interstitial 

 ramparts. 



Coenenchyma shows in sections of expanding edges the streaming layer, very clear and 

 delicate. Its bending upwards and downwards distinctly traceable. The upper layer, which 

 is several cm. thick in massive growths, rises up in the interstitial spaces into flat thin ridges 

 which, in fusing, seldom form ramparts round single calicles, but usually surround two, three, 

 or more calicles in rows. The textm-e of the ridses is a light echinulate reticulum in which a 

 regular palisade arrangement of the fine vertical elements of the reticidum is visible under a 

 pocket lens. Young calicles appear on the slopes of the interstitial ridges like swallows' nests. 



There are two fragments — broken edges — of this coral, which is evidently closely allied 

 to Montipora foveolata. It differs from it, however, in the fact that more than one caUcle opens 

 in the bases of the troughs between the interstitial ridges, and that when only one opens its 

 margin is distinct, i.e. the slope of the ridge does not dip down straight into the fossa, but 

 there is a slight shelf marking the true aperture of the caUcle. 



Another peculiarity of these specimens is the appearance of minute young calicles on the 

 sides of the ridges somewhat Uke swallows' nests, above the level calicles in the bases of the 

 trough. The outer walls of such young calicles are thin and sometimes membranous. 



As in M. foveolata, the ridges are, as a rule, thin, and here and there they are developed as 



