London Insects. 129 



exception of Spiders and Centipedes, and as Swift 

 describes it 



"That curious creature men call a woodlouse, 

 (''Slate beast" is its name in the Highlands) 

 " Which rolls itself up in itself for a house," 



one scarcely knows whether one ought to feel most 

 astonished at the wonderful likeness in unlikeness 

 running everywhere through Nature, which makes 

 such generalisations possible, or at the labour which 

 a conclusion of the kind represents. 



Why should every Butterfly, Beetle, Moth, Fly, or 

 Flea wherever found north, south, east, or west be 

 built up of just thirteen segments, and have just 

 six legs, and how many centuries of quiet work of 

 patient, observant men living and dying many of 

 them absorbed in the one favourite study has it 

 taken to find out with something like certainty that 

 such, improbable as it sounds, is the case ? 



To the second question all sorts of answers have 

 been given at different times, each seeming satis- 

 factory at the moment, but most of them to be 

 written only on sand and washed away by the rising 

 tide of fuller knowledge. 



There are at least three ways in which the six- 

 legged insects may be grouped. One natural division 

 is according to their manner of feeding some suck, 

 others chew or munch. 



The first are spoken of in scientific books as 

 "Haustellate? the last as "Mandibulate" but as this 

 arrangement only gives two classes, it is not of much 

 use. Another way of dividing them is according to 

 the changes which they pass through before reaching 

 the perfect state. 



