74 The Microscope. 



Where these are few in proportion to the size of 

 the eye, they are less regular in shape than when they 

 are numerous. This appears in the eye of the cricket. 

 The irregularity appears most near the edge,, where it 

 takes a sudden bend, and where a set of regular 

 hexagons could not pack together ; and still nearer 

 the edge, some of the lenses have only five, or even 

 four sides. 



Crabs' eyes are composed of hexagons ; those of 

 lobsters and shrimps of squares. 



The eyes of lobsters, crabs, etc., are mounted on 

 a foot- stalk, so that they are rather more movable 

 than those of insects. They are, however, smaller in 

 proportion to the size of the creature's whole body 

 than those of insects usually are. 



And now, passing from the mechanism of the eye 

 to the multitude of other wonders from the animal 

 kingdom, to be observed in any good collection of 

 microscopic objects, we naturally feel embarrassed with 

 riches. See them all understand them all would 

 be the aspiration of many an enthusiastic microscopist ; 

 and no unworthy wish, nor one altogether unattain- 

 able when the privilege of leisure time is added to 

 the advantages of a good microscope, well-prepared 

 objects, good books of reference, and the requisite 

 amount of industry and intelligence. 



I will conclude this section by an account of three 

 curious feet those of the common spider, the house- 

 fly, and boat-fly, the two latter being insects properly 

 so called, and the former belonging to the more highly 

 organized family of the Arachnidce. 



