260 DESCRIPTION OF FIVE NEW SPECIES 



tracks, as may be seen on PI. XI, f. 6, which is the outline of the 

 coot's foot. The coot's foot, also, is flat on the bottom ; and such 

 appears to have been the case with the foot that made these 

 tracks; especially the O. Lyellii; for the O. fulicoides is more 

 rounded at the bottom. 



The sketch, Fig. 6, will show that the claw of the cool's foot is 

 free from an attached membrane, and in this respect it differs from 

 the tracks under consideration. In the Pied-bill Dob-chick, how- 

 ever, [Podiceps CaroUncnsis,) the membrane extends to the end of 

 the claw; as may be seen on the sketch PI. XI, f. 5, which is copied 

 from a dried specimen in the Cabinet of the Boston Natural His- 

 tory Society. The same may be seen in some of the figures of 

 the feet of the Linnean genus Colymbus, in Rees' Cyclopedia, 

 Plate III of Ornithology ; where also may be seen outlines of the 

 feet of the Tringee and. Fulicae, corresponding to Fig. 6. 



Figs. 6 and 5, are of the natural size : and for them I am in- 

 debted to Dr. S. L. Abbot, Jr. of Boston. Fig. 6 shows the right 

 foot of the coot, and Fig. 5, the left foot of the dob-chick. Dr. 

 Abbot adds : " In the last, the hind toe may occasionally touch the 

 ground ; and its extent is, therefore, given. In the first, the hind 

 toe rests on the ground ; and the length of its impression in walk- 

 ing, would vary with the length of the step, as it is articulated on 

 the tarsus above the other toes." 



It is difficult to compare the tracks on stone above described, 

 with the feet of such birds as the coot, the tringae, and the dob- 

 chick, without feehng that both must belong to the same class of 

 animals : and that the one must be a type of the other. I mean, 

 if we make the feet of living animals the standard of comparison. 

 That there may have been animals in the red sandstone period, 

 of a different class, say reptiles, with feet so exactly like our pres- 

 ent birds, as some of the tracks on stone seem to be, it is easy to 

 imagine : especially when we learn that there was at least one 

 extinct reptile, (the pterodactyle,) that walked on two feet. But 

 when we come to examine the feet of all the species of that 

 animal hitherto discovered, we find them with four or five toes 

 pointing forward. We are then left almost to conjecture to sus- 

 tain the opinion that other biped saurians once existed with feet 



