, and Pennatula phosphorea. 333 



pinnae. On the back part of the pinnated portion of the stem of 

 this animal we observe innumerable spicida collected into small 

 groups, and disposed on each side of a mesial longitudinal 

 groove. When viewed through a lens, these slender shining 

 spicula much resemble the groups of setae forming the feet of 

 a nereis or aphrodita, and they all point backwards from the 

 naked part of the stem. On watching the polypi of both 

 these zoophytes when fully expanded in pure sea water, their 

 arms and ciliae were observed remaining like those of the Lo- 

 bularia perfectly motionless, excepting when some floating 

 particles or animalcules impinged against them, which caused 

 them to contract their cilise or their tentacula, and sometimes 

 to withdraw themselves languidly into their sheaths or cells. 

 The only motions of the polypi were those of advancing and 

 retreating to their cells, which they did slowly, and with the 

 same irregularity observed in every other zoophyte, no two 

 polypi and no two pinnae exhibiting any constant uniformity 

 in their motions. The long cilice of these animals are not vi- 

 bratory organs, as in many smaller polypi, but are supplemen- 

 tary tentacula which feel, distinguish, and seize their prey 

 when it strikes against them. By looking through the heads 

 of the extended polypi with a lens, ^ I could perceive a con- 

 stant vibratory motion most obvious in the Virgulariae, within 

 the mouth, apparently produced by minute moving ciliae placed 

 round the entrance of that passage, and minute particles were 

 occasionally seen propelled from the mouth. The whole fleshy 

 substance of both animals became slowly contracted or dis- 

 tended by agitating or renewing their water, and these motions 

 were as languid as the dilating and contracting of an actinia, 

 to which Dr Fleming very justly compares the Pennatulas 

 (Phil, of ZooL ii. 613.) The ViigularicE did not exhibit the 

 slightest power of changing their positions, or of retiring from 

 each other when placed in contact with each other perpen- 

 dicularly in a vessel of sea-water, nor could they turn them- 

 selves by distending their pinnae when they were placed on 

 their faces horizontally at the bottom of the water. The 

 pennatulce showed no power of raising their bodies or swim- 

 ming in the water, even when pinched and irritated ; but in 

 <listending their whole fleshy substance, by absorbing water 



