THE MESOZOIC AGES. 205 



length could not have been less than fifty feet ; per- 

 haps much more. From a single tooth, which has 

 been found, it seems to have been herbivorous; and 

 it was probably a sort of reptilian Hippopotamus, 

 living on the rich herbage by the sides of streams 

 and marshes, and perhaps sometimes taking to the 

 water, where the strokes of its powerful tail would 

 enable it to move more rapidly than on the land. 

 In structure, it seems to have been a composite 

 creature, resembling in many points the contemporary 

 Dinosaurs; but in others, approaching to the croco- 

 diles and the lizards. 



But the wonders of Mesozoic reptiles are not yet 

 exhausted. While noticing numerous crocodiles and 

 lizard-like creatures, and several kinds of tortoises, 

 we are startled by what seems a flight of great bats, 

 wheeling and screaming overhead, pouncing on 

 smaller creatures' of their own kind, as hawks seize 

 sparrows and partridges, and perhaps diving into 

 the sea for fish. These were the Pterodactyles, the 

 reptile bats of the Mesozoic. They fly by means of 

 a membrane stretched on a monstrously enlarged 

 little finger, while the other fingers of the fore limb 

 are left free to be used as hands or feet. To move 

 these wings, they had large breast-muscles like those 

 of birds. In their general structure, they were 

 lizards, but no doubt of far higher organization 

 than any animals of this order now living; and in 

 accordance with this, the interior of their skull shows 

 that they must have had a brain comparable with 



