SEA-MATS AND SHELLY CORALLINES. 77 



Other ariitnal caught bj the bird's head of a Polyzoan, 

 and tightly hekl, would presently die ; and though in 

 its own substance it would not yield any nutriment to 

 the capturer, yet by becoming the centre of a crowd of 

 busy infusoria, multitudes of which would constantly be 

 drawn into the tentacular vortex, and swallowed, it 

 would be ancillary to its support, and the organ in 

 question would play no unimportant part in the ecou- 

 omy of the animal. 



