CORALS AND CORAL-ANIMALS. 103 



beds. Hundreds of these worms were exposed to view in a section of the coral less than 

 one inch square ; they either remained contracted within their respective tubules or wriffo-lincr 

 out, fell through the water to the bottom of the glass dish in which they were under examina- 

 tion. The investigation was continued, with the object of ascertaining whether any distinct 

 organisms were associated with the larger pores. These pores, however, appeared to be 

 hermeticall\' closed — with but one or two exceptions, and in these, worms similar in aspect 

 to, but larger than, those inhabiting the smaller pores were seen protruding from their 

 orifices. It appeared reasonable, under these circumstances, to think that the larger pores 

 probably represented the brood chambers of the adult zooids, and that the entire corallum 

 was built up by the worms that had been placed so conspicuously in evidence. The facts 

 revealed by this investigation of Heliopora, which were fully demonstrated by the author 

 at the time to the satisfaction of Dr. W. G. K. Barnes, R.N., and other officers of H.M.S. 

 Rambler, appeared to differ so essentially from all previously recorded theories concerning 

 the structure and afifinities of the type, that a brief account was forwarded to Nature. 



Meanwhile, a specimen of the Heliopora was conveyed to Thursday Island, placed in 

 a coral pool easy of access, and examined from time to time, for the detection of any new 

 developments. Until the end of five weeks from the day that the specimen was first collected 

 no alteration, was noticed in the external aspect of the coral ; the worms continued to 

 manifest the same active vitality, protruding and extending their tentacles on all sides from 

 the smaller pores, in search of food. The day before leaving Thursday Island a last visit 

 was paid to the coral pool, when, to the author's astonishment, zooids, each with eight 

 pinnate tentacles, were seen projecting from the larger pores. The fact was not immediately 

 realised that these protruding zooids were Alcyonoid polyps. There are also pinnately tentacled 

 annelids or worms, which in such instances as Filograna build up compound calcareous coral- 

 like habitations ; and this supported the conjecture that the larger zooids probably repre- 

 sented matured individuals of the undoubted worms which inhabited the more numerous 

 smaller pores. A rough outline drawing of the protruding zooids as visible at the bottom of 

 the pool was made on the spot ; but, on the specimen being brought to ' the surface of 

 the water for more careful examination, the animals slowly retreated into their respective 

 cells, and they were seen no more in the living state, the specimen being subsequently 

 transferred to spirit. 



Later investigations showed that Professor Moseley's interpretation of the Alcyo- 



narian nature of Heliopora was perfectly correct, with relation to the occupants of the larger 



pores and the construction of the greater mass of the corallum, and that that investigator 



had observed the worm which inhabits the exceedingly numerous smaller pores. To 



what extent these annelids contribute to the formation of the corallum of Heliopora carntea, 



or to the moulding of its characteristic minuter porous structure, remains to be discovered. 



c c 



