5o6 POPULAR SCIENCE MONTHLY. 



are at home in the tree tops; and squirrels, opossums, coons, bears, 

 cats, monkeys, apes, and sometimes man, find up among the branches 

 of a tree the situation that meets pleasure or necessity. 



Launching out into the air, the most difficult path to take, most 

 hazardous and most perilous, but attempted by many different kinds of 

 animals, is another highway. Some faint suggestion of an effort to 

 utilize the air in locomotion is shown by the wind-blown Portuguese 

 man-of-war, and more fully by the aeronautic spider who launches his 

 balloon of silk for aerial flight, but no real success as traveler of the 

 air is found until we reach the group of insects, where wings — true 

 aerial organs of locomotion — become a conspicuous characteristic of 

 the group. How well they have succeeded is testified by the fact that 

 such locomotion has been in vogue with them since early paleozoic 

 time, and, considering their size, the speed and endurance exhibited in 

 air is equaled by no other kind of animal. 



The flying-fish, driven from its native element by pursuing foe to 

 temporary elevation in the air, is a strange abortive attempt to reach 

 this goal, but it has taken too direct a course ever to succeed. It 

 should have first become an air-breathing land animal before at- 

 tempting the soaring act. The frogs and lizards with expanded feet 

 for floating on the air are poor apologies for flying animals, but given 

 time might reach that goal were not the field so fully occupied by more 

 dominant forms. The ancient flying reptiles, known only by their fos- 

 sils, reached a high degree of efficiency, if we may judge by the expanse 

 of wing they show. In their time they were doubtless the dominant 

 types of the air, but they left no legacy to later forms, for the wings 

 of modern groups are formed on different plans and must have been 

 developed de novo or regardless of the reptilian type. 



So now we reach the birds — the truest, most perfect of aerial forms, 

 the animals which, with natural organs, have come nearest to annihila- 

 ting time and space — whose skill in traversing the trackless regions of 

 aerial waste has been the constant envy of man, from early time down 

 to Darius Green, Maxim and Langley and a host of modern inventors. 

 *0 had I wings' in various refrains has been the lament of man till 

 we may expect ere long that the want will be practically supplied. 

 Some birds indeed do not seem to appreciate this gift and have sacri- 

 ficed these organs to adapt themselves to water or to a speedy gait on 

 land, but flight is the dominant mode of locomotion for the group. 

 Some of the mammals, aside from man, have attempted to follow the 

 lead of the birds and the bats have succeeded so well that they are 

 practically cut off from all other modes of locomotion, while flying 

 phalangers, flying squirrels, and others attest the effort in various 

 groups to adopt this rapid though liazardous kind of locomotion. 



