180 EVENINGS AT THE MICROSCOPE. 



dark eye is conspicuous in front, and the six-jointed and 

 bristled limbs radiate from the centre, projecting stiffly 

 on all sides. The second and third pairs are seen to be 

 double, each giving off a branch, which is pencilled with 

 bristles like the principal stem. 



We have not yet done with these tiny Water-fleas. 

 The sediment at the bottom of this jar of water is quite 

 alive with a host of nimble atoms, some of which you 

 may see crawling up the sides of the glass. They are 

 quite distinct from either of the kinds we have been 

 examining, not only in details of structure, which is 

 more identical, indeed, than it seems at first sight, but in 

 habit; for, whtreas they shoot to and fro through the 

 water with great force and rapidity, these can scarcely 

 swim at all ; or, if they do, it is with comparative slow- 

 ness and much apparent effort; though over the smooth 

 side of their glass dwelling, or upon the stems of water- 

 plants, they glide along with much ease and elegance by 

 the quick vibrations of their pencilled feet. 



The form we are now contemplating is distinguished by 

 the name of Cypris, a genus which contains a good many 

 British species. It is more completely inclosed in a shell 

 than even the Lynceus ; and its envelope more truly 

 resembles the shell of a bivalve Mollusk, for the valves 

 are open for more than three-fourths of their circum- 

 ference ; while the portion of the back that is united is 

 sufficiently elastic to allow of some degree of expansion, 

 thus answering the purpose of a hinge. 



ISTow look at the elegant little creature. Its most pro- 

 minent feature is its two pairs of antenna?, one projecting 

 forwards and curved upwards, the other downwards. 

 Both consist of several transparent joints, and are tipped 

 with long clear bristles; but the pencils which tip the 

 upper pair are specially graceful, being as long as the 

 whole shell, exceedingly slender, beautifully curved, and 

 so transparent that they seem formed of spun glass. 



