152 MADREPORARIA, 



SUPPLEMENT TO GROUP II. (Vol. IV. p. 48.) 

 Australian Forms. 



159. Goniopora Great Barrier Reef (i6)13. {G. Queenslandicc (erliadecivca.) 

 (i'l. VIII. fig. 4.) 



[Moreton Bay, coll. W. Saville-Kent ; British Museum.] 



Description. — Tlie corallum is a detached, massive, bean-shaped nodule, which rested, in 

 part at least, upon low prominences of its surface, the tips of which seem to have suffered from 

 contact with tiie substratum. Between these prominences the surface is smooth. 



Tlic caliclcs are nearly flush witli the surface, being only shallow depressions, subcircular, 

 and varying from 1 to 2 mm. in diameter. The walls are only the slight ridges between the 

 depressions and not raised as steep ramparts. They are everywhere obviously composed of 

 tlio tliiuk, peripheral ends of the septa, but occasionally show a tendency to be reticular. 

 The sejita, about twenty, with granular and frosted edges, taper towards the centre, and are 

 usually symmetrically arranged on each side of the directive plane. The missing parts of the 

 typical formula are apparently always those near the directives. The columellar tangle is 

 seldom visible at the surface, being replaced by irregular groups of minute septal teeth or 

 granules, which get smaller anti smaller as the septa taper inwards. Occasionally a few of the 

 granules near the centre show traces of beginning to rise as pali. 



This Goniopora occurs further south than any of the other known representatives of the 

 genus. It seems to liave been lying on coarse sand, some of wliich was found embedded in 

 the small knobs on which the .specimen rested. 



Tlie hal)it of tlie specimen instantly recalls that of certain Porites and Montijwrcs which 

 also lie free on a sandy bottom near the Amirantes Islands in the Indian Ocean. In all of 

 them the calicles are more or less flush with the surface, with the same close skeleton, the 

 same kind of frosted granulations, and the same yellowish-sandy colour. Further, detaclied 

 fragments of other Poi-itcs sometimes acquii-e the same kind of skeleton and colour, compare 

 Vol. V. p. 80 (No. 1904. 10. 17. 37). It is difficult then to avoid the conclusion that the 

 so-called specific characters of this coral are due to its environment. We do not yet know 

 wliether it is an accidental gi'owth, derived peihaps by fracture from some fixed stock, or 

 whether some rejiresentative of the genus has acquired tlie habit of living in this way, its 

 parental polyp having perhaps settled upon some small lou-se pebble or shell which is gradually 

 coated over. 



The specimen is further interesting because patches of it are being killed by an alga 

 which hollows out the skeleton. In the case of G. Great Barrier Reef 6, p. 53, Vol. IV., the 

 alga was mainly confined to the walls, which in that coral are liigh, but here it is in both sejjta 

 and walls ; the former being almost as near the surface as the latter. 



a Zool. iH'pt. 92. L2. 1. 315. 



