THE GEOLOGICAL REC0RT3 



227 



equally large size. The backward prolongation of the head is 

 supposed to show that the powerful muscles required for such 

 immense wings were attached to the head. This is rendered 

 more probable by the skull, nearly 4 feet long, of another still 

 larger species, in which the occipital crest projects a foot back 

 from the head, and which Professor ^Farsli believes had a 

 spread of wdng of 20 or even 25 feet (Fig. 66). 



Fig. 66. — Lateral View of Skull of Pteranodon longiceps. 



From the Cretaceous of North America. One-twelfth nat. size. The jaws are en- 

 tirely without teeth. There is an enormous occipital crest (c) projecting far 

 behind the occiput, to which the mirscles for flight were probably attached; (a) 

 the nares and pre-orbital cavity; (&) the orbit. This species had an expanse 

 of wings of about 20 feet. (From Nicholson's Manual of Palaeontology.) 



We thus see that during the Secondary epoch the great class 

 Reptilia, wdiich had originated apparently during the last 

 stages of the Primary, became developed into many special 

 types, adapted to the varied modes of life wdiich the higher 

 warm-blooded vertebrates have attained in our own time. The 

 purely terrestrial type had their herbivora and carnivora cor- 

 responding to ours in structure and habits, but surpassing them 

 in size; the amphibious or marsh species surpassed our largest 

 existing crocodiles, while the true aquatics almost exactly an- 

 ticipated the form and habits of our porpoises and smaller 

 whales. The air, too, was peopled by the strange Pterodactyls 

 which surpassed the bats in powers of flight, in which they 

 almost rivalled the birds, while they exceeded both in the enor- 

 mous size thev attained. Considering how rare must have been 

 the circumstances which led to tlie preservation in the rocks of 

 these aerial creatures, we may conclude, from the large number 

 of species known to us, that they \u\\<\ have been extremely 

 abundant in middle and late ^Icsozuic times, and that they 



