90 ROYAL SOCIETY OF CANADA 



AsPERiPES CAUDiEER^ Dawson, sp. 



PI. II, figs, la, h. PL VI, fig 5. 



Stride, 3 (to 4) inches (75 mm.); Straddle, 3 inches (105 -mm.). 



Hind foot, length and width each 1^ inches (40 mm.), five toes 

 determinable; the first digit nearly obsolete; the fifth spreading away 

 from the other three, which also spread from each other) but not so much 

 as the fifth. The three other toes are directed somewhat outward; there 

 are claws on these, and probably also on the fifth; the phalange of the 

 two middle toes, bearing claws, is long. The sole sometimes only partly 

 impressed and over one inch wide. There is usually a narrow transverse 

 heel. Angle of digits, I-V=110°; I-II-=70°. 



Fore foot. Small, f of an inch (20 mm.) long and nearly as wide. 

 Has three toes which are widely spread, and furnished with claws. Sole 

 half an inch wide and nearly as long. Angle of digits, II-IV=60°; 

 11-111=50°. The print of this foot is usually wanting; in one in- 

 stance where it is well preserved it is equally distant from the prints 

 of the hind foot before and behind it, and is outside of the line of hind 

 footprints. 



The heavy body of this animal was low, and has brushed the sand 

 forward from the crest of the ridges over which the animal was walking; 

 in this way a broad shallow groove has been produced: on one side of 

 this groove, for a short distance is a naxrow and deeper groove, not 

 exactly in the centre of the track which probably was produced by the 

 tail (hence Dawson's specific name). 



The track of this animal was on coarse grained gray sandstone and 

 tberefore is not well preserved. There are wave-markings upon it 2 to 3 

 inches apart from crest to crest of the ridges. The animal was travelling 

 up the beach, from the water, and it turned somewhat in its course 

 where the first tracks of the series figured were made. In walking tha 

 nails Gif the foot drev.^ the sand in behind them and marred the distinct- 

 ness of the track. The broad furrow made by the dragging of the belly 

 over the sand, the width between the two rows of footmarks, and the 

 short footstep, show that the animal had short legs and a heavy body. 



This fossil footmark was classed by Sir Wm, Dawson with his genus 

 Hylopus. Apart from the fact that it shows the impression of a sole 

 as well as of toes and seemingly should be considered plantigrade, the 

 number of toes of the fore foot which have left an impression are only 

 three whereas in Hylopus as the auth(?r has limited it there are four. 

 It is true that the animal used its claws with vigour in walking, and 

 with these drew up the sand beliind, making a rough instead of a 



