204 EVENESrOS AT THE MICROSCOPE. 



it is elaborately constructed ; for it consists of a mini- 

 ber (not very large) of simple ejes placed beneath a 

 common glassy cornea. Several muscle-bands are at- 

 tached to this compound organ of vision, and are ar- 

 ranjxed so as to form a cone, of which the eve is the 

 base ; these give the eye a movement of rotation upon 

 its centre, which may be distinctly seen. 



All the limbs, including both pairs of antennae, twj 

 pairs of foot-jaws, five pairs of feet, and a pair of tail- 

 lobes, are furnished at each of their many joints with 

 tufts of long hairs ; these aj)pear to act the part of 

 paddles, as the active little animal strikes the water 

 vigorously with all its limbs, for the purpose of pro- 

 gression, and also for the creation of currents in the 

 fluid, which currents subserve a double object, — the 

 bringing constant supplies of water to be respired, and 

 floatincr atoms of food to be devoured. 



In this individual, which is a female, the antennae 

 are nearly equal in size throughout their length ; but 

 in the male, the middle joints of the upper pair are re- 

 markably enlai-ged, forming a large swelling, followed 

 by a sudden conti-action, the first part of which is hinged. 

 All of the true feet, and the second pair of foot-jaws, are 

 divided to the base into two equal branches, so that tlu 

 animal seems to possess no fewer than twenty-six limbs 

 each of which being many-jointed, and each joint, as \ 

 have observed, being set with delicately plumose haii-s, 

 the whole effect is most elegantly light and feathery. 



On each side of the slender tail (more correctly, the 

 abdomen) you see an oval bag connected with the body 

 by an excessively slender thread of communication, and 

 filled tensely with pellucid globose bodies. Like John 

 Gilpin, of equestrian fame, when 



