SEA-FAN MAKERS. 189 



It has been intimated, that in the " sea-fans " there 

 is to be found a horny axis, covered with a fleshy 

 bark, or cortex, from which the polypes protrude. 

 This axis, in the majority of cases, is accurately 

 characterised as horny, for it is composed of a sub- 

 stance very similar, but not identical with that which 

 constitutes the horns and hoofs of animals. Still, 

 there remains a small group in which the axis is not 

 absolutely horny, but partly of the horny substance 

 and partly of carbonate of lime. Of course, both of 

 these substances are secreted and deposited by the 

 polyps. 



A "sea-fan," or Gorgonia, therefore, is a body 

 which is formed by the union of numerous polypes 

 upon a common body, enveloped by a gritty, fleshy 

 substance, containing spicules of lime, and sur- 

 rounding another tree-like secretion, which is its 

 axis, formed of a substance resembling horn, or horn 

 mixed with carbonate of lime, the polypes them- 

 selves being furnished with eight arms, or tentacles, 

 the margins of which are fringed. Bearing in mind 

 these facts, it will be seen readily what the "sea- 

 fans " have in common, and wherein they differ from, 

 their nearest associates. 



It is difficult to enter with precision into the details 

 of the structure of these minute animals, and their 

 secretions, without being exposed to the charge of 

 being " heavy " and " dry," but some excuse, even for 



