AGE OF IlEPTILES. 



they abound. Before he began 

 his observations in 1835, these 

 tracks had been noticed for full 

 forty years by persons who 

 were not aware of their great 

 geological interest. Some are 

 tracks of birds, some of reptiles, 

 and some of animals that had in 

 combination the characteristics 

 of both birds and reptiles rep- 

 tilian birds, as they may be call- 

 ed. In Fig. 141 is represented 

 a slab of sandstone found near 

 Mount Holyoke. The large 

 tracks show that the animal 

 which made them on the mud, 

 now hardened into rock, had a 

 foot 20 inches long and ' - 

 21 wide. It is supposed , 

 that he was a Batra- 

 chian, a toad-like animal, 

 and yet he must have 

 been of the size of an ele- 

 phant. There are tracks, 

 a &, of some smaller ani- 

 mal, and much of the sur- 

 face shows also the im- 

 pressions of rain-drops 

 as distinctly as if they 

 were made yesterday. 

 One of the largest of the 

 birds of that period was 

 the Brontozoum gigan- 

 teum, whose track is 

 given in Fig. 142 (p. 

 242). Its feet were from 

 14 to 20 inches long, its 

 L 



L'41 



