' OF NEW SOUTH WALES. 299 



animals with tubular tentacles disposed in a crown, and commu- 

 nicating with the visceral chamber ; and 2. Podactinia. 



The Cntdaria are divided into two orders — 1. Alcyonaria, 2. 

 Zoantharia, which latter have simple tentacles or ramifying irre- 

 gularly and increasing with age. 



The Zoantharia are again divided into three sub-orders, viz.: — 



1. Actinia, always soft in every part; 2. Antipatharia, with a 

 coriaceous axis and a tissue full of spiculae ; 3. Madreporaria, with 

 a stony calcareous axis. 



The Madreporaria are known by the stellate structure of their 

 polypodom, which arises from the septa or divisions of the 

 visceral chamber. We distinguish in each chamber — 1. The 

 septa ; 2. The calice or cup-like depression of the summit ; 3. 

 The columella or central mass or column independant of the 

 septa and springing from the base ; 4. The wall or partition 

 which bounds the whole chamber ; 5. The casta ov ribs outside 

 the wall which often seem identical with the septa, but generally 

 are quite distinct from them. Madreporaria are divided into five 

 sections — 1. Aporosa, or those on which, the tissue or scleren- 

 chyma is compact ; 2. M. Perforata : sclerenchyma perforated ; 

 3. .If. Tubulata : tubular ; 4th. M. Tabulata : visceral cavity subdi- 

 vided by stages or floors, and the septa rudimentary or hexa- 

 meral ; 5. M. rugosa: sclerenchyma tabulated, but the septa well 

 developed and tetrameral. 



By far the greater portion of our stony corals belong to the 

 first section of Madreporaria Aporosa, indeed they include the 

 larger portion of the whole class. It should be borne in mind 

 therefore that in this section the visceral chamber is open or free, 

 being only transversely subdivided by irregular projections. The 

 septal apparatus is well developed, and the sclerenchyma or 

 stony matter of the wall, &c, is compact. 



This section includes eight principal groups — 1. Turbinolidce ; 



2. Dasmidce (fossil) ; 3. Oculinacece ; 4. Stylophorince ; 5. Echi- 

 noporince : 6. Astreidce ; 7. Merulinacece (one genus only) ; 8. 

 Wungidce. 



