[MATTHEW] NEW GENUS OF BATRACHIAN FOOTPRINTS 87 



progressively shorter to the first digit. The sole was large and rather 

 deeply impressed. 



The fore foot had three toes, of which the outer sets off from the 

 other two, and the middle projects forward somewhat more than the 

 others. The sole projects backward in a prolonged heel. 



This form of footmark is not iincommon on the layers at the 

 Joggins, and,' like Hylopus, had often a rough surface, perhaps owing 

 to the sharp claws with which the toes were furnished. It is necessary 

 to separate it from Hylopus, because there are the impressions of only 

 three toes to the fore foot, and because of the distinct impression of a 

 sole to both fore and hind foot. The fact that there were only three 

 toes to the fore foot also separates it from a number of genera that ha,vo 

 been described by authors. On comparing the fore foot with the hind, 

 it will be seen that the obsolete digits of the fore foot are probably the 

 first and second. 



The irregularity of the footprint in some species of this genus 

 shows the flexibility of the toes, and the name of the genus alludes to 

 the rough and irregular imprints left by animals of this kind. 



Asperipes avipes n. sp. (PI. Figs. 3a and 3&), is the type of this 

 genus. Two other species are known. 



It might be thought that in Asperipes the footprint showing the 

 marks of only three toes is that of the hind foot. In many mammals, 

 and in the alligator among the reptiles the foot with fewest toes is the 

 hind foot. The long heel also of the footmark, determined as the fore 

 foot, is a mark of the hind foot in many dinosaurs, as, for instance, in 

 Anomepus and Otozoum, and it is therefore necessary to explain why 

 it is supposed this anomalous relation of the two footmarks exist inj 

 Asperipes. "We have not seen any consecutive series of footprints of 

 the type species that will determine this relation, and the determination 

 is based on the relation found to exist in the footprints of the other 

 two species. 



In the second species the disparity in size between the print of the 

 fore and hind foot is somewhat greater than it is in the type species, in 

 which we see some indication that the three-toed footmark, being the 

 smaller, is that of the fore foot. But another character of greater im- 

 portance appears in the footprints of this species, there is a series of 

 tracks of this species showing eight footmarks, but of these only one is 

 that of the three-toed foot; from this one might suppose that the com- 

 mon gait of this animal was bipedal, and that it only occasionally 

 touched the fore foot to the ground. If this' was its usual method of 

 progression, it would explain the larger size of the hind foot, and the 

 way in which the toes are spread out. 



