,2 THE GREAT BARRIER REEF. 



upon, and overwhelm, the several masses of living Goniastraea; that are conspicuous in the lett- 



hand corner of the foreground. In aspect and colour this remarkable Alcyonarian bears a 



striking resemblance to coarsely-corrugated, newly-tanned leather. The polyps associated 



with this gigantic polypary are identical in form, size, and colour, with those of Sarcopliyton 



glaiicniii, illustrated by Figs. i8 and i8a of Plate X. of the chromo-lithographic series. The total 



number of polyps contained in the continuous polypiferous encrustment embodied in this 



reef-view presents a problem whose solution would entail the registration of a portentous array 



of figures. 



PLATE XXI. 



GIANT SEl-SNEMONE, DISCOSOMI HIDDONI, 



It will be readily comprehended that the anemone which forms the subject of this illustration 

 is a very giant of its class, in association with the record that examples have been met with by 

 the author in which the expanded disk measured no less than from eighteen inches to two feet in 

 diameter. It is tolerably abundant throughout the Barrier district as far south as Flat Top Island 

 off Mackay, occurring chiefly in the shallow pools at about half or three-quarters ebb. A 

 characteristic feature of this species is the contour and aspect of the tentacles. When the 

 anemone is fully extended and in complete repose, its disk presents the appearance of being 

 covered with minute, perfectly spherular, bead-like papilla;, which are distributed thickly on the 

 periphery, and in gradually attenuating linear series towards the central mouth. On closer 

 examination the spherular papillae are found to be mounted on short footstalks, these structures, 

 as a whole, corresponding morphologically with the subulate tentacles of all ordinary sea- 

 anemones. The slightly elongate and distinctly capitate contour of these modified tentacles may 

 be recognised towards the superior, right-hand, margin of the periphery of the photographic 

 reproduction, where a number of these organs are slightly pressed to one side. The almost 

 globose shape of the tentacles, in their condition of fullest expansion, is not represented in this 

 illustration in as marked a degree as frequently obtains. The anemone, when photographed, had 

 been kept in a basin, with frequently-changed sea-water, for several days, and was in a somewhat 

 abnormally puckered-up, contracted state. It is only towards the lower peripheral border, 

 indeed, that any of the tentacles present a near approach to their fully-extended appearance. 



A more adequate idea of the characteristic aspect of the tentacles of this anemone in their 

 normal condition of inflation may be obtained by a reference to Plate II. of the coloured series, 

 and in which segments of the disks of two diversely-coloured individuals are delineated in their 

 natural size. It will be observed that a brilliant-hued fish and a crustacean are included in this 

 coloured plate. These both represent what are known technically as "commensal" species; they 

 live on the most intimate terms of friendship with the anemone, swimming freely in and out of its 

 mouth, and making its body or somatic cavity a harbour of refuge into which they adroitly retreat 



