156 THE GREAT BARRIER REEF. 



sents the most important group associated witii the phenomenon of reef-construction. It will 

 not be attempted in these pages to describe each and every species that has been observed 

 or collected by the author in the Barrier region categorically. To accomplish such a purpose, 

 doing full justice to the subject, would require a volume in itself, of a size larger than the 

 present one. Attention will be here directed only to those most conspicuously attractive or 

 constructively important species, that are either prominently represented in the accompanying 

 photographic reef-views, or are typically illustrated in their natural colours in the succeeding 

 chromo-lithographic plates. 



The production of a simple but complete list of all the varieties collected in this productive 

 district is, as a matter of fact, also an impossibility. The examination, comparison, and 

 determination of the actual affinities, and in many instances the diagnostic definition, of new, 

 or hitherto imperfectly - described, species, is in itself a task demanding years for its 

 accomplishment. Fortunately, on arriving in England with his collection, the author found 

 that Mr. George Brook, F.L.S., well known for his admirable report on the Cliallciigrr 

 Antipatharia, or black corals, had been entrusted with the compilation of the long-promised 

 Catalogue of the British Museum Madreporaria, and had been occupied throughout the previous 

 year with the study and nomenclature of the single genus Madrepora. The author's collection, 

 which he presented to the Trustees of that Institution for incorporation with the National 

 series, consequently arrived, as the saying runs, just in the nick of time. Hitherto, the 

 number of species of reef corals definitely associated with an Australian habitat has not, 

 according to the Challenger reports {Reef Corals, Vol. XVI. p. 22), exceeded sixty-one. The 

 genus Madrepora exemplified by the author's Barrier district collection, which has alone, so 

 far, been investigated by Mr. Brook, numbers over seventy species, including a large incre- 

 ment of new ones. The remaining varieties, of which it is impossible at present to give 

 an exhaustive catalogue, are likel}', at all events, to bring the number of authenticated 

 Australian reef corals to at least two hundred. A general estimate of the various generic 

 groups, together with a rough approximate calculation of the variety of species they sevei-ally 

 contain, is nevertheless embodied in the appendix to this volume. In so far as the genus 

 Madrepora is concerned, the catalogue, worked out and furnished to the author by Mr. Brook 

 is a complete one. 



A nearer examination may now be made of the specific varieties of corals that enter 

 most conspicuously into the composition of the Great Barrier reefs. On the system of 

 classification adopted in the list forming the appendix, the first natural group or family to 

 attract attention is that of the Euphylliaceae. The members of this group are distinguished 

 by the possession of a coral-skeleton or corallum, that takes the form of hemispherical 

 clusters of individual coral cups or corallites, formed by repeated bifurcation, which are 

 either entirely independent of one another at their extremities, or occasionall}- united in 



