THE LOWER FOEMS OP LIFE. 119 



The British species (P. pkosphorea) is very common on our coasts, 

 especially in Scotland, and is taken in numbers attached to the bait 

 of the fishermen's lines, especially, according to Ellis, when this 

 bait is a mussel. It is from two to four inches long, and of a 

 purple colour, except at each extremity, where it is pale orange. 

 When irritated it is beautifully phosphorescent. A difference of 

 opinion exists among naturalists, whether the Sea-Pen is perma- 

 nently fixed in the ground, or has a certain extent of locomotion. 

 Grant, after Cuvier, Pallas, and Bohadsch, has adopted the latter 

 view, and expresses himself about it as follows : " A more singular 

 and beautiful spectacle could scarcely be conceived than that of 

 a deep purple P. . phosphorea, with all its delicate transparent 

 polypi extended, and emitting their usual brilliant phosphorescent 

 light, sailing through the still and dark abyss, by the regular and 

 synchronous pulsations of the minute fringed arms of the whole 

 polypi." 



Dr. Johnston, however, in his British Zoophytes, doubts whether 

 the Sea-Pens have any locomotion, and quotes Lamarck and 

 Schweigger as authorities in his favour. Johnston, with much 

 reason, observes, that it is most improbable that a compound animal 

 so low in the scale should have the power of locomotion, and states 

 that he has never known them to move their position when placed 

 in a basin of water. " They inflate the body until it becomes in a 

 considerable degree transparent, and only streaked with uninter- 

 rupted lines of red ; they distend it more at one place, and contract 

 it at another ; they spread out the pinnae, and the polyps expand 

 their tentacles, but still they never attempt to swim or perform any 

 effort towards locomotion. Our fishermen believe that they are 

 fixed at the bottom with their ends immersed in the mud, and the 

 paleness of the base, when viewed in connection with the preceding 

 observations, go far, in my opinion, to prove this statement to be 

 correct." 



The phosphorescence of the Sea-Pen proceeds entirely from the 

 polyps. Fig. 165 (frontispiece) is one of these polyps magnified. 



Another of what are sometimes called bark-covered Corals is 

 illustrated in the plate by a figure of the well-known red Coral of 

 commerce (Fig. 162, frontispiece), which is produced by an Alcyo- 

 narian polyp belonging to the genus Corallium. A portion of the 

 ccenosarc and its polyps have been removed in three places in 

 the figure, and what is seen laid bare is the bony, calcareous, 

 richly and variedly-coloured substance of which coral ornaments are 

 formed. This Coral is found principally in the Mediterranean, 

 where it forms one of the staple articles of maritime industry. 

 The somewhat clumsy-looking form in which it grows, as seen in 



