470 THE AQUARIAN NATURALIST. 



cilia in constant vibration, causing by their united 

 efforts powerful and rapid currents, which, sweeping 

 over the entire surface of the gills, hurry towards the 

 mouth whatever floating animalcules or nutritious 

 particles happen to come within the limits of their 

 action, and thus bring streams of nutritive molecules 

 to the very aperture through which they are con- 

 veyed into the stomach, the lips and labial fringes 

 acting as sentinels to admit or refuse entrance, as the 

 matter supplied is of a wholesome or pernicious cha- 

 racter. So energetic, in fact, is the ciliary movement 

 over the whole extent of the branchial organs, that if 

 any portion of the gills be cut off with a pair of 

 scissors, it immediately swims away, and continues 

 to row itself in a given direction as long as the cilia 

 upon its surface continue their mysterious move- 

 ments. The tenuity of the individual cilia is inde- 

 scribable, 



" Fine as Arachne's thread or gossamer ;" 



while, such is the velocity of their movements, that 

 it is only by their effect upon the surrounding water 

 that they are at all distinguishable, 



" Like that spun vapour when 'tis pearl'd with dew." 



Around the margin of the mantle is arranged a row 

 of greenish, metallic-looking lustrous beads, emulating 

 in their brilliancy so many gems, and indeed by no 

 means unlike those precious stones familiarly known 

 as " catVeye diamonds." The nature of these glow- 

 ing specks remained completely problematical until 

 Polij after much elaborate research, pronounced them 

 to be visual organs, and conferred upon the animal 



