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EVENINGS AT THE MICROSCOPE. 



. You have doubtless observed, while gazing on the 

 animal, a peculiar glittering appearance along its sides, 

 mingled in certain lights with brilliant rainbow-reflections. 

 Now let us take an opportunity, when it approaches the 

 side of the glass, to examine this appearance with a lens. 

 The globe, you see, is marked by longitudinal bands, eight 

 in number, set at equal distances, and ranging like meri- 

 dians, except that they do not quite reach to either pole. 

 These bands are the seats of the motile organs, which 

 are highly curious, and in some sort peculiar. 



Each band is of considerable width in the middle, but 

 becomes narrower towards the extremities. It carries a 



CYDIPPE. 



number — usually from twenty to thirty — of flat thin 

 membranous fins, set at regular distances, one above the 

 other, which may be considered as single horizontal rows 

 of cilia, agglutinated together into flat plates. Each plate 

 has a rapid movement up and down, from the line of its 

 insertion into the band, as from a hinge, and thus strik- 

 ing the water downwards, like a paddle. The whole 

 band may be likened to the paddle-wheel of a steamer, 

 except that the paddles are set in a fixed line of curvature 



