The Flying Lizards of the Secondary Rocks. 445 



characteristics except the possession of the means of aerial loco- 

 motion — the Pterodactyles. 



Amongst the Verlebrata the power of flight was formerly 

 considered to belong especially and almost exclusively to birds. 

 In the auks and penguins, however, we find birds whose wings 

 are useless for flight, but serve admirably for swimming ; and 

 the ostrich, cassowary, emu, apteryx, etc., have no wings 

 (properly so called) at all. 



We are all familiar with the Mammalian type of flying ani- 

 mals, the bats, in which the finger-bones and membrane of 

 the fore-hand are modified, so as to form organs fitted for the 

 purposes of sustained and rapid flight. In the Galeopithecus 

 and certain squirrels we have instances of other mammals im- 

 perfectly adapted for flight by a wide expansion of the skin on 

 both sides of the body, from the neck to the hinder extremities, 

 which serves as a parachute. Short flights are likewise per- 

 formed by some fishes (as the Dactylopterus, for instance), 

 which have their pectoral fins enormously enlarged, and capable 

 of sustaining the body for a brief interval when they leap out of 

 the water into the air ; but their respiratory arrangements pre- 

 clude a long absence from their native element. 



In the Reptilian class we also have an illustration of imper- 

 fect flight in the little Draco volans, a lizard, which has an 

 expanded membrane on each side of its body, and supported by 

 the horizontal extension of the first six pairs of false ribs. It is, 

 however, incapable of motion, and only sufficient to buoy up the 

 creature in springing from bough to bough in pursuit of insects. 

 That this capability of flight, which attains its highest develop- 

 ment in birds whose respiration and circulation is the most 

 active of all " warm-blooded" animals, should be assumed by 

 certain mammals may seem remarkable, but that we should 

 discover it exercised in a high degree of perfection among 

 reptiles — a class so sluggish in the respiratory functions that 

 they have been designated " cold-blooded" — seems at first in- 

 credible ; indeed, the fossil remains of these curious creatures 

 when first discovered gave rise to the wildest speculations. In 

 1784, Collini, an eminent German naturalist, attributed them to 

 TJnbekanntes Seethier {unknown sea-beasts) ; Hermann, to a 

 creature " between a mammal and a bird ;" Blumenbach, to a 

 "water-bird;" Spix, to a species of vampire bat. 



It is to the illustrious author of the Ossemens Fossiles 

 that we are indebted for the first true determination of the place 

 in nature which these flying Saurians held. It was Cuvier 

 who, in 1S01, described the " Reptile volant" from the 

 lithographic stone, and in 1809* he gave it the appropriate 



* Ann. du 'Museum, xiii. p. 421, t, 31. 



