CCELENTERATA : ALCYONARIA. 



I6 5 



division of the Zoantharia sclerodermata ; others, again, such as Favosites 

 and its allies (fig. 79), belong to the Perforate division of the Z. scleroder- 

 , and are very nearly related to the Poritidcz ; others are referable to 



Fig. 79. A, Portion of the corallum of Favosites favosa, of the natural size. B, Portion 

 of four corallites of Favosites Gothlandica,, enlarged, showing the tabulae and the 

 "mural pores " or openings in the walls of the corallites. 



the Alcyonaria; while others, lastly, are of uncertain affinities. It is clear, 

 therefore, that the section Tabulata can no longer be retained as a division 

 of the Zoantharia sclerodermata, or as a division of the Corals of any 

 zoological value. The section Tubulosa (including only the Palaeozoic 

 genera Aulopora and Cladochomis or Pyrgia} is also of no zoological value, 

 in the present state of our knowledge. The forms included in it are 

 simple or compound, with trumpet -shaped thecae, rudimentary septa, 

 and few or imperfect tabulae ; and they are probably referable to the 

 Alcyonaria. 



CHAPTER XIII. 



ALCYONARIA. 



ORDER II. ALCYONARIA. The second great division of liv- 

 ing Actinozoa is that of the Alcyonaria, denned by the pos- 

 session of polypes with eight pinnately -fringed tentacles, the 

 mesenteries and somatic chambers being also a multiple of four 

 (eight). The corallum, when present, is usually sclerobasic, or 

 spicular ; if "theca" are present, as is rarely the case, septa are 

 wanting or rudimentary. 



The Alcyonaria or "Asteroid Polypes" differ numerically 

 from the Zoantharia in having their soft parts arranged in 

 multiples of four, instead of five or six, as in the latter, whilst 

 the septa are not in pairs. Their tentacles, too, are pinnate, 



