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 whereas 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 slowness 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 pen- 

 cilled 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 re- 

 sembles the shell of a bivalve Mollusk, for the valves are 

 open for more than three-fourths of their circumference ; 

 while the portion of the back that is united is sufficiently 

 elastic to allow of some degree of expansion, thus answer- 

 ing the purpose of a hinge. 



Now 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 trans- 

 parent that they seem formed of spun glass. 



