CCELENTERATA : ACTINOZOA. 



121 



of a sclerobasic, rod-like corallum, sometimes associated with 

 sclerodermic spicules. 



Pennatula (fig. 32), or the " Cock's-comb," consists of a free 

 coenosarc, the upper end of which is fringed on both sides 

 with featherlike lateral pinnae, which bear the polypes ; whilst 

 its proximal end is smooth and fleshy, and is probably sunk in 

 the mud of the sea-bottom. This latter portion of the cceno- 



Fig. 32. Pennatula phosptwrea. 

 (After Johnston.) 



Fig- 33- Pennatulidae. 

 Virgularia mirabilis. 



* (i A portion of the 

 stem in the living con- 

 dition enlarged ; b 

 Portion of the stem in 

 its dead condition. 



sarc is, likewise, strengthened by a long, slender, styliform 

 sclerobasis, resembling a rod in shape, whilst spicula occur 

 also in the tentacles and ectoderm. The general colour of 

 Pennatula is a deep reddish purple, the proximal extremity of 

 the coenosarc being orange-yellow. Our British species (Pen- 

 natula phosphorea) varies from two to four inches in length, 

 and is found on muddy bottoms in tolerably deep water. Its 

 specific name is derived from the fact that it phosphoresces 

 brilliantly when irritated. 



In Virgularia (fig. 33), which, like Pennatula, occurs not 

 uncommonly in British seas, the actinosoma is much longer 



