THE FOSSIL FOOTMARKS OF THE UNITED STATES. 131 



Geologists and Naturalists at Washington, in 1844, and published 

 in the forty-seventh volume of the American Journal of Science, I 

 described four other species of tracks ; and in the same work for 

 July, 1847, Vol. IV., New Series, I added two additional species. 

 Several other new species have remained in my possession unde- 

 scribed, from the pressure of more important duties. My present 

 memoir will embrace forty-nine species, not simply of footmarks, 

 but of the animals that made them, so far as their characters can 

 be ascertained. Of these, twelve were certainly quadrupeds, four 

 of them probably lizards, two chelonians, and six batrachians ; 

 two were annelids, or molluscs ; three are of doubtful character ; 

 and the remaining thirty-two species were bipeds, so far as our 

 present information extends. Eight of them seem to have been 

 thick-toed tridactylous birds ; fourteen others were probably nar- 

 row-toed tridactylous or tetradactylous birds ; two were perhaps 

 bipedal batrachians ; and the remaining eight may have been 

 birds, but will more probably turn out to have been either lizards 

 or batrachians. Of these forty-nine species, forty-seven occur in 

 the valley of Connecticut River, in Massachusetts and Connecticut. 



I have little doubt that many will at once pronounce it impossible 

 that the tracks of so large a number of animals should be distin- 

 guished in a few quarries in that valley. I shall shortly present the 

 characteristics of each particular track, from which the comparative 

 anatomist and zoologist can judge whether I have multiplied the 

 species too much. But there are a few general considerations, 

 which may take away all antecedent improbability as to the ex- 

 istence and discovery of so large a number. 



And, first, we have now found these tracks in at least twenty- 

 one places, scattered through an extent of nearly eighty miles ; that 

 is, from the Horse Race, three miles above Turner's Falls in Gill, 



