﻿ANACKOPORA. - 171 



Calicles as conspicuous holes raised only on slight protuberances, with faintly projecting, 

 sharp margins. The older calicles on the thicker stems may reach 1 ram. in diameter of 

 aperture, while the young calicles appearing near the tips of the branches are about • 5 mm. 

 The aperture is tilted a little in the direction 'of growth. The lower side of the projecting 

 margin is often thin and jagged, sometimes a series of points. The septa generally irregularly 

 and feebly developed round the margin, but occur in the fossa in two nearly symmetrically 

 arranged cycles. Lamination of the radial structures only indicated by directives and 

 primaries. The primaries (of wliich one or two in the direction of growth are larger and 

 thicker as directives) are very short and do not reach to the half radius circle ; the secondaries 

 are mere points. Fossa open and deep. 



The axial streaming layer of the coenenchyma is about 2 to 2*5 mm. in diameter and 

 consists of an open arrangement of stout pronounced bands running in the direction of growth. 

 This forms the tapering tips of the branches, and in it the young calicles appear. The 

 thickening of the branches and stems is entirely due to the appearance and growth of the 

 cortical layer. This is in marked contrast to the streaming layer and is very dense, merely 

 traversed by canals which appear as pores or more freq^uently as furrows gyrating about on 

 the surface. The otherwise smooth surface is frosted over with miniite white granules or 

 points. 



This species is peculiar in the comparatively slight protuberance of the calicles, and the 

 septa being vertical rows of points, as in Montipora, and showing only a slight tendency 

 to lamination, the directives and primary septa being frequently plate-like as if they were 

 parts of interrupted lamellse. 



The two original type specimens upon which the genus was founded by Mr. Ridley in 

 1884 are in the possession of the Museum. 



The larger specimen is a portion of a low straggling stock, some 12 cm. long and rising to 

 about 6 cm. from its dead base. It seems to have been broken into seven pieces, two which 

 have been refixed in their places, while four are still detached. The bases of the stems die 

 down progressively and corrode. Here and there also young branches are dead and corroded. 



The smaller is a detached bi'anch which has continued to live, the surface oi fracture 

 having been covered over by a growth of spongy coenenchyma in which young calicles are 

 appearing. 



Both these specimens, which are a faint pink colour, are figured in the original paper by 

 Mr. Eidley. 



a, h. Keeling Islands (deep water inside reef). H. 0. Forbes, Esq. 



("With four fragments of a.) 



2. Anacropora gracilis. 

 Anacropora gracilis, Quelch, Chall. Eep., Eeef Corals (1886) p. 170, pi. x. figs. 6, 6a. 



Description. — Corallum a close tangle of thick stems and branches, the latter not 

 tending to grow upwards but to fuse irregularly together. The component stems and 

 branches of nearly uniform thickness, from 3 to 5 mm., twisted and bent in all directions. 



z 2 



