ANIMAL FLIGHT 105 



are only seen high up among the trees on dying enter the 

 ground and there become preserved as emeralds. Flying 

 creatures, especially birds, butterflies, winged mammals and 

 winged serpents, are familiar subjects for more or less conven- 

 tionalized designs, especially on pottery and totem poles, and 

 coats of arms, but more or less on all ornamented objects, and 

 on all t^pes of family or individual insignia. 



Of all known kinds of animals almost two-thirds can fly, or 

 at least glide through the air, and of land living creatures 

 the flying sorts number about three-quarters of the whole. 

 There are more than 400,000 kinds of flying insects, more than 

 20,000 flying birds, 600 flying mammals, all but a few of which 

 are bats, possibly 60 flying fishes, and a few flying lizards, 

 snakes, and molluscs, and perhaps frogs and crustaceans. 



Of flying creatures some will fly only at rare intervals and 

 under strong compulsion, and others, like the flying ants and 

 termites, while strong fliers, make only a single flight after 

 which they discard their wings by cutting them off with their 

 mandibles or by breaking them off at a hne of special weakness 

 and again become ground living. From such as these the 

 amount of time spent on the wing by animals increases step by 

 step until we reach the chimney swifts w^hich fly practically 

 throughout the daylight hours, the insect eating bats which 

 seem to fly most, if not ah, the night, and the albatrosses and 

 related sea-birds which in some localities appear to fly for days 

 and nights together without rest. 



The birds are the most familiar of the larger flying creatures. 

 Flying birds range in size from the smallest humming-birds, 

 which are much smaller than our common North American 

 kinds, to the South American condor, with very broad wings, 

 and the wandering albatross with very narrow wings spreading 

 eleven feet or more. 



It is a curious fact that the larger the animal the smaller in 

 proportion are the wings. Insects have relatively much larger 

 wings than birds, and small birds have relatively much larger 

 wings than big ones. In the mosquito for each pound of body 



