232 AN ATTEMPT TO DESCRIBE THE ANIMALS THAT MADE 



some cases in which the foot slid forward as it came to the ground, 

 with such a vis a tergo as its weight would give ? Yet the im- 

 pressions of its feet are as distinct and undisturbed, as if they 

 had been each one put down with the nicest care. I hesitate, 

 therefore, to assert that leaping was the animal's mode of pro- 

 gression. 



The form of the feet, and the number and position of the toes, 

 as well as the broad posterior part of the foot, seem to ally the 

 genus Anisopus to batrachians. But what living batrachian places 

 its feet in walking as did these fossil species ? It is, indeed, quite 

 remarkable. Although the feet were of very unequal size, yet it 

 would seem from Plate 22, fig. 1, that it walked very much like 

 such quadrupeds as the cat, the dog, and the fox ; that is, the 

 tracks vary but little from a right line ; nor is the axis of the foot 

 turned much aside from the line of direction. Indeed, its mode of 

 walking was much more like that of a mammiferous quadruped, with 

 long, perpendicular legs, than like that of sprawling reptiles. I 

 have almost persuaded myself that these animals are marsupial 

 quadrupeds. For we know that this tribe did exist in the oolitic 

 period, and would it be strange, if they should be shown to have 

 appeared one geological period earlier, that is, in the triassic pe- 

 riod ? The presumption, however, from the general analogies of 

 fossil nature is, that they were batrachians ; but if they were so, 

 their structure must have been quite peculiar. For the present, 

 however, I leave them among the batrachians. By comparing their 

 tracks with those of the Proteus, given on Plate 19, fig. 3, the 

 form of the toes will be seen to be quite similar ; but how different 

 the mode of progression ! 



As to the Hoplichnus, its mode of walking must have been 

 similar to that of quadrupeds ; but since we know as yet so little 



