440 THE AQUARIAN NATURALIST. 



it. They are well placed for such a purpose, as their 

 incessant gaping and swinging must enable them 

 readily to detect the presence of trespassers. 



Mr. Gosse, in his most useful ' Manual of Marine 

 Zoology for the British Isles ' (a work indispensable 

 to the sea-side visitor who wishes readily to identify 

 the varied productions of our coasts), suggests that 

 the " bird's-head appendages/' by seizing passing 

 animals and holding them in their tenacious grasp 

 until they die, may be a means of attracting the 

 proper prey of the Bryozoon to the vicinity of its 

 mouth. The presence of decomposing animal sub- 

 stances in water, he observes, invariably attracts 

 crowds of Infusory animalcules, which then breed 

 with amazing rapidity, so as to form a cloud of living 

 atoms around the decaying body, quite visible in the 

 aggregate to the unassisted eye; and these remain 

 in the vicinity, playing round and round, until the 

 organic matter is quite consumed. A tiny Annelid, 

 or other animal, caught by the " birdVhead " of 

 a Polyzoon, and held tightly, would presently die; 

 and though in its own substance it would not yield 

 any nutriment to the captor, 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 thus play 

 no unimportant part in the oeconomy of the animal. 



Among so many conflicting opinions and surmises, 

 we must leave every microscopist to decide for him- 

 self; we merely state the case as we find it, simply 

 wishing the reader as much pleasure as we ourselves 



