CORALS AND CORAL-ANIMALS. 143 



ORDER II.— ZOANTHARIA. 

 Polyps resembling sea-anemones, but united so as to form composite colonies. 



ORDER III.— MADREPORARIA. 

 Including all so-called "Stony-corals" and typical reef-constructing corals. 



ORDER IV.— ANTIPATHARIA. 

 Polyps with six tentacles only, or a multiple of that number, secreting a dense horny or wood- 

 like uniaxial or branching " sclerobase." 



ORDER v.— ALCYONARIA. 



Polyps possessing eight, usually pinnate, tentacles ; either naked, associated with a fleshy 

 corallum, or secreting a horny or spicular uniaxial sclerobasic corallum ; the latter, though 

 usually tree-like, is in some instances tubular. 



ORDER I.— ACTINARIA. 



The non-coral forming or skeletonless solitary Actinaria, popularly known by the familiar title 

 of sea-anemones, occur in great variety among the reefs of the Great Barrier system, and are 

 remarkable in some instances for their large dimensions, in others for their brilliant colours, 

 and in a third series for the complex structure of their tentacles. 



In working out the nomenclature and affinities of the Barrier Reef representatives of the 

 Actinarian order, the author has received substantial assistance from Professor A. C. Haddon, of 

 the Royal College of Science, Dublin, the author of several valuable monographs on the British 

 Actiniae. The authority named having also spent some months in Torres Strait, making the 

 Actinaria, among other things, a subject of special study, is consequently familiar with the 

 outward form and growth habits of a considerable number of the species described and illus- 

 trated in this volume. Professor Haddon and the author have, to a certain extent, "gone 

 shares " in the division of the Actinozoarian spoils of the Torres Strait district, and, by 

 mutual consent, have left to one another the nomenclature and description of conjointly collected 

 species that proved to be new to science. In order to make the Barrier district catalogue 

 of Actinaria as complete as possible, the names of all the forms met with by Professor Haddon 

 that are distinct from the types collected by the author, are included in the list appended 

 to this volume. 



In chronicling the more remarkable varieties of the ordinary or simple sea-anemones indigen- 

 ous to the Great Barrier Reef, attention may be appropriately directed, in the first instance, 

 to certain giants of their race referable to the genus Discosoma. Two particularly large species of 

 this genus occur in considerable abundance among the reefs as far south as Mackay, and are 

 readily distinguished from one another by the character ol their respective tentacles. In the one 



