HAUNTS AND HABITATS 33 



this by no means implies that they themselves were dwellers in 

 an inland district. As a matter of fact, the Stonesfield beds 

 are a lagoon-deposit, into which the remains of land animals 

 and plants were washed down by rivers ; and the pterodactyles 

 were probably inhabitants of the shores of the lagoon itself. 

 This inference is supported by the fact that pterodactyle re- 

 mains are unknown from the purely fresh-water and terrestrial 

 deposits of the Dorsetshire Purbeck. Consequently, it seems 

 probable that pterodactyles were in the main frequenters of 

 coast-lines, and that they did not take the place of birds in in- 

 land districts. This is the more likely seeing that at any rate 

 as early as the Upper Jurassic true birds {Archceopteryx) were 

 already in existence. 



On land, throughout the Mesozoic epoch, huge dinosaurs 

 played the part of the great land mammals of the later Tertiary 

 period and the present day; while rhynchocephalians, fresh-water 

 tortoises, and crocodiles fulfilled the role of lizards and snakes 

 and the modern representatives of the last-named group. 

 Whether there were arboreal reptiles (other than pterodactyles) 

 during the Jurassic and Cretaceous periods, we have no means 

 of knowing. 



At the present day all this predominance and exuberance 

 of reptilian life have completely passed away. The dominion of 

 the air, or such claim to the same as could be maintained by the 

 pterodactyles, has been completely lost, not a single existing 

 reptile having the power of true flight. Much the same may be 

 said with regard to the " command of the sea " formerly possessed 

 by the reptilian class, for at the present day there are no truly 

 pelagic reptiles (if we except the mythical sea-serpent) save the 

 sea-snakes, none of which exceeds five or six feet in length, and 

 most of which are less. Turtles — both leathery and otherwise 

 — are it is true in the main pelagic reptiles, but they go ashore to 

 deposit their eggs, and are thus not comparable to ichthyo- 

 saurs and plesiosaurs on the one hand and to whales on the other. 

 The only other reptiles which can in any true sense be called 

 marine are the Indian Crocodilus porosus and the Galapagos 

 sea-iguana (Amblyrhynchus cristatus) ; but these spend a large 

 portion of their time on land, and the former is by no means 

 exclusively a denizen of the coasts but is rather an amphibious 

 land reptile which takes partly to a marine life. It should be 



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