CCELENTERATA : ZOANTHARIA. 157 



Edwardsia (fig. 71, A) has a thin imperforate base, and lives 

 buried to the lips in mud or sand, the middle of the body be- 

 ing protected by an epidermic investment. This curious form 



Fig. 71. A, Edward si a callimorpha ; B, Ilyanthus Mitchelli, of the natural si/e. 

 (After Gosse.) 



exhibits, as shown by Prof. Allman, many singular peculiarities 

 of internal structure, amongst which the fact that the soft parts 

 are in multiples of four may be specially noted. The distin- 

 guished authority just mentioned regards Edwardsia as in 

 some respects intermediate between the Zoantharia and Alcy- 

 onaria, and as related to the extinct Rugosa. Peachia and 

 Cerianthus also lived buried in the sand, both having the base 

 perforated by an orifice, whilst the latter further protects itself 

 by the secretion of a loose, membranous, non-adherent tube. 



FAMILY III. ZOANTHID^:. The polypes in this family form 

 colonies united by a fleshy or coriaceous coenosarc, in the 

 shape of a crust or of creeping roots, and they have no power 

 of locomotion. The ccenosarc may be strengthened by em- 

 bedded spicules, adventitious grains of sand, or other foreign 

 bodies. Examples of the family are Zoanthns and Palythoa. 



SUB-ORDER II. ZOANTHARIA SCLEROBASICA. The " Black 

 Corals" or Antipathida, which compose this group, are always 

 composite, consisting of a number of polypes united by a thin 

 fleshy ccenosarc, which is spread over and supported by a simple 

 or more commonly branched horny axis or " sclerobase" The 

 tissues are not furnished with calcareous secretions, and the 

 polypes have in general six simple tentacles. 



The corallum or skeleton of the Antipathida is of a horny 

 consistence, its form simple or branched in a more or less 

 complicated and plant-like manner, and its surface smooth or 



