122 



LOWER INVERTEBRATES. 



walls of a tube in which the worm lives surrounded by the case, bearing the relation- 

 ship of a true messmate to the coral upon which it is found. 



Of the true Halcyonoida the genus Hdlcyonium of the Halcyonid^ is one of the 

 most interesting, which is sometimes designated by the suggestive name of dead-men's- 

 fingers, looking not very unlike a human hand with the fingers remaining as mere stumps. 

 Although in general ai^pcarance Halcyonium resembles the soft corals, well-marked 

 spicules of beautiful shapes are found regularly arranged in its walls. 



The commofa sea^fan, Mhipidogorgia flabellum, which we select as illustrating the 

 GoEGOsriD^, is one of the most common Halcyonoids of our tropical and semi-tropical 

 seas. The fan-like shape which the colony has is the result of the fission of many 

 lateral branches, large and small, forming a network often of great fineness. The sea- 

 fan has a hard central axis, and a still softer rind which can be easily broken off, and 

 at the death of the animal is almost wholly deciduous. In this softer rind are found 



the spicules, and from it the animals directly arise. 

 There is a great variety in the forms of the differ- 

 ent genera of sea-fans, and the colors are sometimes 

 very striking; in many, bright reds and yellows 

 predominate with purples and browns. 



The sea^whips, of which there exist a great vari- 

 ety of forms, assume either the shape of low, branch- 

 ing, shrub-like zoophytes, or long, unbranched, 

 straight or spiral rods. Their colors are sometimes 

 black, often light brown, and occasionally, as in a 

 Chrysogorgia from deep water, golden. 



One of the best known of all the Halcyonoids 

 is the genus CoralUuw. so much prized as the orna- 

 mental coral of commerce. The greater quantity 

 of this coral which is used is gathered in the Medi- 

 terranean where the most extensive fisheries are 

 FIG. 117. - coraiiium rubrum, xed coral. gjtuated on the western coasts of Italy, the' shores 

 of Sicily and Sardinia. The city of Naples, 

 where the cutting of the coral into ornaments is 

 a great industry, is a great centre of coral com- 

 merce, and many pounds of the more precious 

 varieties are yearly sold there. The commercial 

 value of different coral fragments depends upon 

 the size, but more especially on the tinge of color 

 which they have. The pink rose-color is esteemed 

 the most valuable, while " ruby " varieties are 

 ranked among inferior wares. Much, of course, 

 also dej)ends in individual specimens upon free- 

 dom from blemish, and purity of color. The 

 coral has from the earliest times been cut into 

 cameos by lapidaries, and its use in ornamentar 

 tion reaches far back into classical times. The 

 word has been derived from the Greek, Koqtj, 

 daughter, a highly fanciful comparison of these most beautiful gems to the daughters 

 of the sea goddesses. 



^m.-;^ 



Pig. 118. — Red coral polyps, enlarged. 



