Ill 



LECTURES ON EVOLUTION 87 



of my friend Professor Marsh, with whom I had 

 the opportunity recently of visiting the precise 

 locality in Massachusetts in which these tracks 

 occur. I am, therefore, able to give you my own 

 testimony, if needed, that the diagram accurately 

 represents what we saw. The valley of the Con- 

 necticut is classical ground for the geologist. It 

 contains great beds of sandstone, covering many 

 square miles, which have evidently formed a part 

 of an ancient sea-shore, or, it may be, lake-shore. 

 For a certain period of time after their deposition, 

 these beds have remained sufficiently soft to 



FIG. 2. TRACKS or BRONTOZOUM. 



receive the impressions of the feet of whatever 

 animals walked over them, and to preserve them 

 afterwards, in exactly the same way as such im- 

 pressions are at this hour preserved on the shores 

 of the Bay of Fundy and elsewhere. The dia- 

 gram represents the track of some gigantic 

 animal, which walked on its hind legs. You see 

 the series of marks made alternately by the right 

 and by the left foot ; so that, from one impression 

 to the other of the three-toed foot on the same 

 side, is one stride, and that stride, as we mea- 



