162 Fossil Footprints of the Connecticut Valley. 



of birds were discovered in 1835, their resemblance to the feet 

 of existing birds was so palpable, so absolute, that their origin 

 was instantly recognized; and when the celebrated footsteps 

 upon the sandstone of Hildburghausen were discovered about 

 the same time, the laws of analogy were apphed to solve the 

 mystery, which resulted in the belief that the animal by which 

 they were made had its type in living species, and this opinion 

 was not long after fully corroborated by the discovery of the ani- 

 mal's bones. In fact, as the teeth of animals indicate the feet, 

 and both teeth and feet indicate the intermediate organs, it is a 

 sound conclusion that the order may be reversed — viz. the feet 

 may indicate the teeth, and consequently the several organs that 

 constitute the animal economy. 



It is fortunate for the investigation of these unknown foot- 

 steps, that the exact knowledge concerning the German impres- 

 sions is available in arriving at a satisfactory conclusion ; for the 

 resemblance between these remote examples is perhaps as com- 

 plete as will be found upon comparison with the feet of living 

 animals. This resemblance, aside from the vast disparity of 

 size, is intimate ; the main distinction consisting in the unequal 

 number of toes, the American specimens having four and the 

 European five each ; a difference which of itself only separates 

 them into species, the essential type still existing in each. But 

 the peculiar similitude, and the most apparent and indeed most 

 valuable, is the disproportion in respect to size between the ante- 

 rior and posterior feet. The latter are thrice greater than the 

 former, and this distinction points to the living type which is 

 found in the Batrachian order of reptiles ; or possibly it may exist 

 in the lowest grades of mammiferous animals, the same inequality 

 or lack of symmetry being also observed in them. Yiewing these 

 sandstone vestiges to indicate either class, and associating them 

 with ornithic impressions, the laws of analogy refer the animals 

 by which they were made to the condition of those existing 

 species which are supposed to be their representatives. It is 

 a doctrine now well established, that the remarkable footprints 

 of birds are due to aquatic varieties allied to existing Grallas 

 or waders — birds inhabiting margins of waters, and traversing 

 muddy shores and shallow bottoms which were alternately sub- 

 merged and exposed to the sun's action. The existing Batra- 

 chians and numerous kinds of the Grallse occur promiscuously, 



