FLYING DRAGONS. 131 



they breathe passes, not into their lungs only, but penetrates to 

 the remotest parts of their system, filling their very bones with 

 life, and endowing them with activity and animation adapted to 

 their active aerial existence. It may, therefore, be argued that 

 Pterodactyls breathed much in the same way ; that their bones, 

 too, were supplied with air by an elaborate system of air-sacs, 

 and that they had lungs like those of birds. We cannot, how- 

 ever, stop there, but are led on by physiological reasoning to 

 conclude that the circulation of the blood must have been rapid, 

 and that the heart was like that of birds and mammals, four- 

 celled. It would therefore follow — since birds and mammals are 

 warm-blooded — that Pterodactyls were also. Such, at least, is 

 the view of Professor H. G. Seeley, vvho says of the Cambridge 

 specimens, "That they lived exclusively upon land and in air 

 is improbable, considering the circumstances under which their 

 remains are found. It is likely that they haunted the sea-shores, 

 and, while sometimes rowing themselves over the water with their 

 powerful wings, used the wing-membranes, as the bat does, to 

 enclose their prey, and bring it to the mouth. 



" The large Cambridge Pterodactyls probably pursued a more 

 substantial prey than dragon-flies. Their teeth are well suited 

 for fish, but probably fowl and small mammals, and even fruits, 

 made a variety in their food. As lord of the cliff, it may be 

 presumed to have taken toll of all animals that could be 

 conquered with tooth and nail. From its brain it might be re- 

 garded as an intelligent animal. The jaws present indications of 

 having been sheathed with a horny covering." 



Probably the large Pterodactyls of the Cretaceous period, 

 soaring like albatrosses and giant petrels over the surface of the 

 ocean, co-operated with the marine reptiles, such as Ichthyosaurs, 

 Plesiosaurs, crocodiles, and others, as those sea-birds now do with 

 the whales, porpoises, and dolphins, in reducing the excessive 

 numbers of the teeming tribes of fishes, and in maintaining the 

 balance of oceanic life. 



