NO. 3 



GRAND CANYON FOSSIL FOOTPRINTS — GILMORE 



45 



given for this conclusion, though their slightly larger size may have 

 influenced his decision. The relative position of these tracks suggests 

 that their identity may be the reverse of Matthew's conception. The 

 same condition prevails in the trackway now before me, but no posi- 

 tive evidence in solution of this suggestion is offered and for the 

 present Matthew's identification will be followed. Between the rows 

 of tracks is a distinct, well defined groove probably made by a 

 dragging tail, which registers the movement of the animal as indicated 

 .by the undulating character of the impression. 



A second series of tracks of this sj^ecies is found on the up])er 

 side of the slab carrying the basi-relief tracks of Hyloidiclmus bifur- 

 catus (No. 11,598, U. S. N. M.). It is a short trackway that is in 



Comparative Measurements 



No. 11,537 

 U, S. N. M. 



Type of 

 Dromillopus 

 quadriiidus 



Length of stride 



Width of trackway 



Length of pes track.... 



W'idtli of pes track 



Length of manus track. 

 Width of manns track. , 



36 



33 



9 



mm. 

 26 



18 



9 



accord in all particulars with the type specimen. The tail drag is not 

 continuous as in the tyi^e but left its trace only on the crests of the 

 rijiple marked surface across which the trail runs. 



Genus HYLOPUS Dawson 



Hylopus Dawson, J. W., Proc. Trans. Roy. Soc. Canada, Vol. 12, 1895, p. yy. 



The genus Hylopus was briefly characterized by Dawson as fol- 

 lows : "Smaller footprints [than Sauropus Lea], digitigrade, and 

 made by animals having a long stride and hind and forefeet nearly 

 equal. Five toes. Probably footprints of Microsauria and possibly 

 of Dendrerpeton.'' In all Dawson described five species. These 

 named in chronological order are : Hylopus logani, H. hardingi, 

 H. caudifcr, H. minor and H. trifidus. All are from the Coal Measures 

 of Nova Scotia. 



Subsequently Matthew * reviewed the genus and reached the con- 

 clusion " that there is so much variation in the form of these foot- 



^ Proc. Trans. Roy. Soc. Canada, Vol. 10, 1904, pp. 82-85. 



