2l8 



CHAPTER VIII. 



ALCYONARIA. 



" As for your pretty little seed-cups, or vases, they are a sweet confirmation of 

 the pleasure Nature seems to take in superadding elegance of form to most of her 

 works. How poor and bungling are all the imitations of art ! When I have the 

 pleasure of seeing you next, we shall sit down — nay, kneel down — and admire 

 these things." — Hogarth to Ellis. 



The Alcyonaria are so designated from their principal type, that of 

 Alcyonium. The species are all marine. The Alcyonaria may be 

 defined as Actinozoa in which each polype is furnished with eight 

 pinnately fringed tentacles. The chambers into which the body is 

 divided are some multiple of four. The corallum is often dense, 

 sometimes consisting, however, of calcareous spicules, and unlike 

 that in the Zoantharia, never showing traces of septa. We shall see, 

 farther on, that among the Gorgonidse the coral ceases to be spongy 

 and cellular ; that its axis assumes a horny consistence, which be- 

 comes often even stony ; but the external barky layer, which is 

 t!ie special lodging of the polyps, always remains soft on the surface. 

 We shall have a general idea of the organisation, habit, and mode of 

 multiplication among the Alcyonaria when we come to treat of the 

 precious coral and its strange histor)'. The class Alcyonaria may be 

 divided into many orders. We shall consider — I. The Tiibiporidoi. 

 II. The Gor^onidx. III. The Painatidida:. IV. The Alcyonidoc. 



I. THE TUBIPORID^ 



form a group consisting of several species, which live in the bosom 

 of tropical seas, in which the Coral Islands form so prominent a 

 a feature. The group is exclusively formed of the curious genus 

 Tubipora. 



The Tubipora is a calcareous coral, formed by a combination of 

 distinct, regularly-an-anged tubes, connected together at regular dis- 

 tances by lamellar expansions of the same material. The aggregate 

 formation resulting from this combination of tubes constitutes a 

 variously-shaped mass, which often attains a very considerable size. 



