114 



KNOWLEDGE. 



[JlNE 1, 1891. 



forms, all these insects are furnished with two pairs of 

 wings, which dififer, however, greatly in structure. Thus, 

 while in the Dratjon-llios, wliich in this respect may be 

 regarded as tlio more generalised representatives of the 

 order, both pairs of wings are large and membranous ; in 

 the Grasshoppers, Cockroaches, and Earwigs the front 

 pair are leathery, and serve as wing-covers to the hinder 

 pair, which are folded beneath them in a beautiful, fan- 

 like manner. Whereas, however, in the Cirasshoppers 

 the first pair of wings still take some small share in 

 fiigbt, in the Earwigs they are extremely small, and serve 

 solely OS covers. The Earwigs, tlicrcforc, which many 

 people believe to be incai)able of flight, represent the 

 extreme of wing-specialisation in this group of Insects. 



This closes the list of flying creatures found among the 

 Invertebrates, and we pass, therefore, to the Vertebrates, 

 where we find our first examples of flight among the class 

 of Fishes. In this group, however, in spite of assertions to 

 the contrary, there is no instance of true flight; such fishes 

 as are able to fly at all merely doing so after the spnrious 

 manner. The longest flights are made by the 



about 7 inches. Its sides, limbs, tail, and head are 

 furnished with loose expansions of skin which, becoming 

 inflated with air, act as a parachute in the long, flying 

 leaps which the creature is able to take from tree to tree. 

 The true Flying Lizards, which range from India to the 

 Philippines, have their parachutes constructed after a 

 totally different fashion. In these creatures the last five 

 or six ribs arc greatly elongated to support an expansion 

 of the skin of the flanks, which forms a fan-like wing on 

 either side. The late Prof. Moseley described tliese 

 lizards m the Philippines as flying so rapidly from branch 

 to brancli that the extension of their parachutes could 

 scarcely be observed ; and also states that some kept on 

 board ship were in the habit of flitting from one leg of the 

 table to another. 



Since the extinct Flying Dragons or Pterodactyles of 

 the Mesozoic epoch, wliich are the only reptiles capaljle of 

 active flight, have been described at length in a previous 

 article, our allusion to ihcm will here be brief. These 

 extraordinary creatures, as shown in Fig. 3, were fur- 



FiG 2.— The Flying Fish 



— Uj:stoi;4.tiiin ur a Long-Tailed PxEiiOUAcTVLii. 

 {After Marsh.) 



Itli Xalural Size. 



well-known Flying Fishes (Fig. 2) of most of the warmer 

 seas, in which the flrst pair of fins are greatly elongated for 

 this purpose. These fishes rise from the water with an 

 upward impulse made by the sides of the body and fail, 

 and tliey may remain above the surface for a distance of 

 200 yards. They do not usually reach a height of more 

 than a few feet above the water, although they occasionally 

 spring so high as to alight on the decks of ships. There 

 are few more beautiful sights than to watch from the 

 bows of a large ocean steamer a shoal of Flying Fish as they 

 rise one after another, witli their quick meteor-like flight, 

 and then as suddenly disappear beneath the dark waters. 



Flying Fish, it may be observed, are first cousins of 

 the common Herring. The only other Fish endued with 

 the power of flight are the Flying Gurnards, which belong 

 to a totally different group, and of which there are three 

 kinds inhabiting the Mediterranean and most tropical 

 seas. All of them are larger and heavier than the true 

 Flying Fishes, although they fly in the same manner. 



It has been stated that a Frog from the Malay region 

 uses the large webs on its feet as a kind of parachute in its 

 descent from the trees on which it dwells to the water, 

 but later researches do not lend countenance to this idea ; 

 and our next examples of flight must accordingly be 

 drawn from the class of true Reptiles. Among living Rep- 

 tiles there is no instance of true flight, although two 

 groups are endowed with the power of spurious flight. 

 The first example of this is the Flying Gecko, a small 

 lizard, belonging to that peculiar group so well known in 

 tropical climates from their habit of nmning up and down 

 the walls of dwelling-houses. The Flying Gecko is an 

 inhabitant of Borneo, Java, Ac, and attains a length of 



nished with tliin membranous wings, which were supported 

 in front by the arm and forearm near the body, and at 

 their extremities by the greatly extended joints of a 

 finger corresponding either to the ring or little finger of 

 the human hand. The membranous expansion was con- 

 tinued down the sides of the liody to embrace the legs and 

 the upper part of the tail ; while in at least some of those 

 species in which the tail was long, its extremity was fur- 

 nished with a racket-shaped expansion of membrane (as 

 in Fig. 2), probably used as a kind of rudder during flight. 

 Some of these creatures were of enormous dimensions, 

 having an expanse of wing estimated at upwards of 2.'j 

 feet. That they were endowed with the power of true 

 flight is perfectly evident from their general structure ; 

 as is especially shown by the strong ridge developed on 

 the breast-bone for the attachment of the muscles neces- 

 sary for the down-stroke of the wings. Their mode of 

 flight was probably very similar to that of Bats, which 

 they appear to have resembled in their wing-membranes, 

 although the support of these membranes, as we shall 

 subsequently see, was arranged on a totally different plan 

 in the two groups. It is, perhaps, superfluous to add that 

 any resemblances existing between Pterodactyles and 

 Birds are solely due to then- adaptation to a similar mode 

 of life, and that there is not the remotest genetic con- 

 nection between them. 



We come now to the Birds, in which true flight has 

 attained the fullest development, and the whole organiza- 

 tion is profoundly modified to suit the exigencies of a 

 more or less completely aerial mode of life. It is true, 

 indeed, that certain birds, such as the Ostrich, Cassowary, 

 and Penguins, are totally incapable of flight ; but this 



