New Genera of Batrachian Footprints. 107 



failed not in hollow of the ripple where the impression 

 might naturally be wanting, but on the ridge of the wave 

 mark ; from this one might suppose that the weight of 

 the animal was carried by the four-toed foot, which would, 

 therefore, be the hind foot. 



But when an examination of the footprints of the 

 second species of this genus is made, there is much greater 

 reason for concluding that the three-toed foot is the fore 

 foot. The impression is not half as large as that of the 

 four-toed foot ; and, moreover, while in the latter the toe 

 prints are arranged on one side of the print of the sole, in 

 the former they are arranged radially around it. 



Megapezia n. gen. 



The peculiar shape of the print of the hind foot appears 

 to separate this from any described genus, though there is 

 a figure given by King in American Journal Science, with- 

 out any name attached, which, in its very large sole, may 

 be compared to Megapezia ; that, however, is represented 

 as having five toes to the hind foot, while in this new 

 genus there are only four. Yet while the number of 

 toes on this foot is four, that on the fore foot is five ; 

 it thus reverses the number observed in such Palaeozoic 

 footprints as have nine toes on the two feet collec- 

 tively. To this relation, in the number of the toe prints, 

 we have a parallel in the footprints of the alligator, 

 which also has four toes on the hind and five on the fore. 

 The resemblance extends to the attitude of the toes, 

 which are turned forward in the hind foot, but radially 

 arranged in the fore foot. There is this distinction, how- 

 ever, that the peculiar backward curve of the fifth digit 

 of the hind foot in Megapezia is not found in the alligator. 



In the hmd foot of Megapezia the fifth digit sets off 

 from the others, and the end is strongly curved backward 

 The toes are rather short and blunt (though perhaps hav- 

 ing claws) ; the second, third and fourth digits are some- 

 what grouped, and directed forward and the first appears 



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