SEA-FAN MAKERS. 183 



colour, or almost that of wet sand, or of a more 

 or less bright orange. We have often seen them 

 adhering to the scallop-shells exposed for sale in fish- 

 mongers' shops, but, of course, in a dead condition. 

 When dredged up, fresh from the sea, and placed in 

 a vessel of sea-water the polyps expand, and then 

 the mass, which before was so uninteresting, becomes 

 quite enchanting. 



It will be remembered that the Actinoid polypes, 

 of which the sea-anemones are the type, have their 

 tentacles and internal septa a multiple of six> but the 

 Alcyonoid polypes, or those of which the " sea-paps," 

 or "dead man's fingers," is the type, have eight fringed 

 tentacles. To this group belong also the sea-pens 

 (Pennatula), the sea-fans (Gorgonia), the organ- 

 pipe coral, and the well-known " red coral." The 

 animals in all these are very similar, and have the 

 common distinguishing mark of eight fringed ten- 

 tacles, but the sea-paps are flexible, containing spi- 

 cules of carbonate of lime scattered amongst their 

 tissues, and without the hard rigid central axis which 

 is present in the sea-fans, except in one family, to 

 which the pipe corals belong, in which the animals 

 secrete slender tubes of carbonate of lime. In the 

 sea-fans, on the contrary, there is a hard, horny axis, 

 of greater or less thickness. In some cases the axis 

 is so slender that the coral (if we may so call it) does 

 not stand erect, but hangs pendulous from the rocks. 



