ALCYONARIA. 257 



490, and which form compound clusters or commu- 

 nities by budding. The Sea-pens and Renillas are 

 Polyps which are arranged on a more or less ex- 

 panded disk, which is connected with a sort of stem 

 or peduncle, by means of which the community may 

 move about or fix itself in the sand or mud. The 

 Sea-pens are so called from their resemblance to 

 a quill. The Renilla, Figure 4S8, found on the coast 

 of the Southern States and of South America, looks 

 like a broad leaf attached to its leaf-stalk ; and when 

 the purple disk is covered with the expanded Polyps, 

 as seen in the cut, it is a very beautiful object. The 

 form of a separate Polyp is shown in Figure 489. 



The Gorgonias abound in tropical seas, but some 

 kinds are also found in temperate regions. The forms 

 are exceedingly various. Figures 490—494, and many 

 of them are very delicate and beautiful, often bearing 

 a very close resemblance to plants ; in all, however, the 

 Polyps are short, and secrete a solid central axis of 

 coral. This axis is plainly shown in Figures 492 and 

 494. One of the most common and striking forms of 

 the Gorgonias is the Sea Fan, which is more or less 

 broad and fan-shaped, the branches in many cases run- 

 ning together so as to form a network. Figure 491. 

 One form of the Gorgonias, the Primnoa, Figure 494, 

 is found even as far north as St. George's Banks and 

 the Bay of Fundy. But the one which has the greatest 

 popular interest is the Red Coral, Coralliutii riibruiii. 

 It is obtained mainly in the Mediterranean. The coral 

 fishers go out in boats, and are provided with a large 

 wooden cross, which is loaded with stone in the center 

 and has hempen nets attached to each of its arms. 

 While one man is constantly raising and letting fall 



NAT. HIST. AN. — I7 



