When Darkness has fallen. 105 



evolutions of the otter in its native element are 

 the poetry of motion minus only the metre. 



When almost the whole of the insect-world 

 has folded its wings in sleep, there is a> class of 

 night-flyers whose hours of activity 'are those of 

 darkness. Among the more interesting of these 

 is the male glow-worm the English lantern-fly 

 whose light may be plainly seen as he flits 

 past, pale and ghostly against the dark back- 

 ground of some deeply-foliaged bank or shadowy 

 wood. Then there is the great army of night- 

 flying moths, whose nocturnal wanderings present 

 such a weird appearance in the darkness, and 

 whose life-history contrasts so sharply with the 

 sunny dalliance of their butterfly cousins. As 

 moths have to contend with the night winds their 

 constitution is more robust than that of the 

 rhopolocera, or day-fliers. Their bodies are 

 thicker, their wings narrower and more strongly 

 nerved. As they settle themselves on corrugated 

 bark or grey stones to their deep, diurnal sleep, 

 their sober and inconspicuous colouring in- 

 variably saves them even from detection. In 

 many species this daily trance is so profound 

 that a slumbering insect may be transfixed 

 and never detect the occurrence until twilight 

 again comes round. But if the closely-folded 

 upper wings are quiet and sober in colouring 

 this is only for Drotective reasons ; for brilliant 



