THE FOSSIL FOOTMARKS OF THE UNITED STATES. 



181 



Table of the Ratio of the several Characters in the Species of this 

 Group. — It will afford the zoologist and comparative anatomist a 

 better means of judging of the grounds on which the foregoing spe- 

 cies have been proposed, to present at a glance, so far as it can be 

 done in figures, the relations between the several characters in differ- 

 ent species. I hope in this way to satisfy naturalists, that such dif- 

 ferences in the tracks could not have belonged to mere varieties as 

 to age or mode of progression, nor have resulted from the character of 

 the mud, but must have required different species of animals to pro- 

 duce them. In other words, I hope to show that these differences 

 are quite as great as they are between the tracks of different living 

 species. In constructing the table, I have taken 100 as the highest 

 number in the preceding details of the characters, and calculated 

 the proportion which the same character in the other species bears 

 to this maximum. It may happen, as in the second column, that a 

 character is at a maximum in several species. 



