THE FOSSIL FOOTMARKS OF THE UNITED STATES. 



211 



lizards ; whose feet certainly have a general resemblance to the 

 tracks of these animals. On the other hand, the resemblance 

 between the front part of the foot of the genus Trifenopus and 

 that of certain birds is very striking, as the sketches on Plate 

 20, copied from Gray's Genera of Birds, subfamily Columbinse, 

 will show. Fig. 2 represents the foot of the Lopholaimus an- 

 tarcticus ; figs. 3 and 4, the feet of Cathartes fcetens ; and fig. 5, 

 the foot of a species of Gryphus. But the fact is, these are birds 

 which for the most part never walk upon the ground, and cer- 

 tainly never upon a muddy shore ; so that we may be sure that 

 this accidental resemblance does not indicate any real affinity. 

 Upon the whole, I am more inclined to refer this group to the 

 lacertilian tribe than to birds, although the evidence does not 

 seem very decided. 



Table of the Ratio betiveen the several Characters of this Group, on 



a Scale of 100. 



JVo/e. — The three species of Harpedaciylus are omitted in the above table, be- 

 cause they are so obviously unlike the other species that minute comparisons seem 

 unnecessary. 



