Fossil Footprints of the Connecticut Valley. 161 



distinction between this variety (denominated Batrachoidichnites 

 Deweyi by Mr. Hitchcock) and that marked fig. 2 is so manifest, 

 that they are at a glance seen to be dissimilar.* The slender toes 

 and disproportionate length of stride of the latter variety are pe- 

 culiar distinctions. In the great number of Ornithichnites I 

 have studied, I do not remember an instance where this dispro- 

 portion of the feet and stride was so unequal. The shortest step 

 of the sandstone bird is rather less than that of this diminutive 

 quadruped, while the area of the foot is several times greater ; 

 hence the four-footed animal, although extremely small, must 

 have been elevated upon legs bearing a corresponding relation to 

 its attenuated toes. These quadrupeds, congregating promiscu- 

 ously with the ancient birds, probably derived the materials of 

 their support from the same element ; and it remains to be con- 

 sidered whether the extinct species have their representatives in 

 the living, or in other words, whether from the arrangement and 

 configuration of the impressions, the natural affinities of the an- 

 cient animals can be determined by comparison with those that 

 now live. 



This problem can only be solved by applying the potential 

 law of correlation of function. If the dental or osseous systems 

 could be obtained, the restoration of the animal would not be a 

 difficult task in competent hands ; and with the perfect cast of 

 its foot, it would seem that a conclusion almost as satisfactory 

 might be reached ; for the fashion of an animal's foot is an indi- 

 cation of its character scarcely less valuable than the peculiar 

 structure of the teeth and bones. The mutual correspondence, 

 or the indispensable relation between the several systems uniting 

 to execute the designs of organization is so unerring, that by the 

 discovery of one organ the others are inevitably indicated. The 

 footprints of all animals with which we are intimately acquaint- 

 ed, irresistibly lead us to determine the kind making them ; and 

 this principle is so universal, that if we can find an existing ani- 

 mal whose footprint shall resemble the fossil impressions, we 

 may conclude that there is a necessary resemblance throughout 

 the entire organization of both animals. When the footmarks 



* The resemblance of Dr. Deane's figure to that given by Dr. Hitchcock of his 

 .B. Dewej/i is certainly very strong. Compare fig. 10«, PI. Ill, p. 308, Vol. xlvii, 

 of this Journal, with the figure by Dr. Deane accompanying this article. — Eds. 



Vol. XLviii, No. 1.— Oct.-Dec. 1844. 21 



