38 THE GREAT BARRIER REEF. 



at home, and were subsequently photographed. Being there subjected to surroundings precisely 

 identical with those under which they naturally exist, their tentacles, as will be observed, were 

 extended in a more complete measure than obtains in the specimen examined under the artificial 

 conditions previously described. 



The upper illustration of Plate XXIV. depicts a species of the genus Fungia, apparently 

 identical with F. discus, that is extremely abundant on the reefs in the neighbourhood of Port 

 Denison. It differs from the preceding species in the finer serration of the septal edges and in 

 the relatively small dmiensions of the tentacles. The subject of the present illustration is of 

 interest as representing by far the most prolific colony of "Nurse-stocks" of this or any other 

 species of Fungia that has fallen within the author's observation. l"he supporting fulcrum is in 

 this instance the dead corallum of an adult Mushroom-coral of the same species, having the lower 

 third ot its oral surface covered by an encrusting species of Montipora. Within the remaming 

 superficial area are crowded together no fewer than thirteen stalked, immature, coralla of sizes 

 varying from less than one quarter of an inch to one inch and a half in diameter. Ten of these 

 are distinctly visible in the photographic reproduction, the remaining three being hidden beneath 

 the expanded disks of the larger individuals. The extent to which they may be distorted by 

 crowding is instructively illustrated by the misshapen contours of the impinging peripheries 

 of the two contiguous pairs located near the centre of the selected fulcrum. It is a moot 

 point whether this luxuriant colony of Nurse-stocks arose fortuitously from different sources, 

 or in a single embryonic swarm from some more distant corallum, or whether they may not 

 represent the product of the expiring vital energy of the defunct adult corallum to which they 

 are united. This latter interpretation appears to be the most reasonable. It is worthy of note 

 that in the majority of instances these attached juvenile coralla represent the first tentacular disk 

 produced, the stalk being smooth and devoid of any scar. In a few cases, however, including the 

 smallest cup-shaped corallum visible towards the upper left-hand side, the cicatrix demonstrating the 

 separation from the stalk of a previously developed tentacular disk is as conspicuous from a lateral 

 point of view as in the figure of a Nurse-stock oi Fungia crassitentaculata included in the preceding 

 plate. Numerous Nurse-stocks of this same species, F. discus, were collected in the Port Denison 

 reefs, but, with few exceptions, as single individuals only, attached to the dead coralla of other 

 Madreporaria or to a rock foundation. As the season of the year exercises a probable influence 

 on the greater or less abundant development of Fungia Nurse-stocks, it may be recorded that 

 the Port Denison examples were gathered in the month of August, 1889, that being one of the 

 coldest months south of the equator. The Adolphus Island examples of Fungia crassitentaculata 

 were collected early in June, 1890, and were obtained as late as September in the previous 

 year on the fringing reef of Albany Island, which forms the eastern boundary of the picturesque 

 Albany Pass, situated within a few miles of Adolphus Island. 



