122 EVENINGS AT THE MICKOSCOPE. 



whicli, if you did not know it, you would never think 

 of connecting with the grab from which it has pro- 

 ceeded ; so totally different is it in form, in structure, 

 and in motions. 



We shall easily find some in our basin that have 

 passed into this stage. Yes, here is one, which will 

 please to take its place in the glass trough with its 

 younger brothers. How strange the transformation ! 

 It reminds us of a lobster, though, of course, the re- 

 semblance is only cursory. With the naked eye we 

 see that the thorax is greatly enlarged, not only ac- 

 tually, but proportionally ; that it forms an oval mass, 

 occupying some five-sixths, at least, of the entire ani- 

 mal ; the rest apparently being taken up by a slender, 

 many-jointed abdomen, which curves round the great 

 thorax, and, bending under it, ends in an excessively 

 delicate, transparent, swimming-plate. It is this curving 

 abdomen, with its terminal swimmer, and its back- 

 ward strokes in swimming, that constitute the resem- 

 blance to a prawn or lobster. 



If we now bring a low power with the reflected 

 light of the Lieberkuhn to bear on it, we shall see the 

 progress the animal has made in this its change of rai- 

 ment. The thorax shows on its sides the future winars, 

 crnmpled and folded down, the nervures of which we 

 can discern distinctly. The elegant little head, too, can 

 be well made out ; its eyes, now perfectly marked with 

 the numerous hexagonal facets that belong to the ma- 

 tured organs of vision in these creatures ; its antennce, 

 like slender rods, folded down side by side along the 

 inferior edge of the thorax ; the short palpi lying out- 

 side these ; and within, both the lancets and piercers 

 that are destined to subserve the blood-sucking propen- 



