140 THE OCEAN WORLD. 



The stalk of the polypidom is hollow in the centre, having a long 

 slender hone-like substance, which is white, smooth, and square, hut 

 tapering at each extremity to a fine point. The polyps, which are 

 fleshy and white, are provided with eight long retractile tentacula, 

 beautifully ciliated on their inner edge with two series of short pro- 

 cesses strengthened with crystalline spicula. The mouth in the centre 

 of the tentacula is somewhat angular, hounded by a white ligament, a 

 process from which encircles the base of each tentaculum, which thus 

 seems to issue from an aperture. The ova lie between the membranes 

 of the pinnae ; they are globular, of a yellowish colour, and by a little 

 pressure can be made to pass through the mouth. The polyps are 

 distributed with more or less regularity in such a manner that one of 

 the extremities of the common axis is always naked : this part has been 

 compared to the tubulous part of a feather. The stem, common to the 

 colony, is a solid central axis, more or less developed, which is covered 

 with a fleshy fibrous substance, susceptible of dilatation and contraction. 



The Pennatulidse comprehend three genera ; namely, those with 

 polyps on bipinnate wings, having according to Dr. Johnston 



Polypidoms plumose, in ..... Pennatula. 

 Polypidoms virgate, or wand-sLaped . . . Virgularia. 

 Polypi, unilateral and sessile . . . . ) 

 Polypidom, linear-elongate } 



In the genus Pennatula, the polyps are disposed in transverse 

 rows upon the outer and inner edge, in a series of prolongations in 

 the form of a feather. These winged species of polypidom are somewhat 

 scythe-shaped, well developed, and furnished with a great quantity of 

 pointed spiculae, which are constituted of bundles at the base of the 

 calyx. The space between the two rows of appendages is sometimes a 

 tissue, sometimes scaly, sometimes granulous. Of the Pennatula five 

 species are known, and all of them appear to be gifted with phos- 

 phorescent properties. We may note among these species Pennatula 

 spinosa (Fig. 61), which inhabits the Mediterranean, and takes its 

 name from its colour ; Pennatula phosphorea, which abound in most 

 European seas, being found in great plenty, clinging to the fishermen's 

 lines round our own northern shores, more especially when they are 

 baited with mussels. 



P. phospliorea is of a reddish purple, the base of the smooth stalk 

 pale ; the raches roughened with close-set papillae, and furrowed clown 



