210 EVENINGS AT THE MICROSCOPE 



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 vibra- 

 tions 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 enclosed 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 circumfer- 



ence; 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. 



Now look at the elegant little creature. Its most promi- 

 nent feature is its two pairs of antennae, one projecting 

 forward and curved upward, the other downward. 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. 



Another peculiarity is that there seems to be but one 



