NO. 9 GRAND CANYON FOSSIL FOOTPRINTS GILMORE 5 



and in the Lyons sandstone of Colorado. The latter is regarded by 

 Henderson ' as late Pennsylvanian, but Willis T. Lee, in an unpub- 

 lished manuscript, reaches the conclusion that the sandstones carry- 

 ing the footprints in Colorado are Permian, which would seem to 

 be more nearly in accord with the evidence furnished by the fossil 

 tracks. Doctor Lee, in a letter under date of June i8, 1925, has 

 kindly furnished the following statement in advance of the publica- 

 tion of his paper : 



In this manuscript it is shown that the rocks formerly called Lyons include 

 representatives of two distinct formations, one of Pennsylvanian age and one of 

 Permian age and that the name Lyons sandstone is now restricted by the 

 U. S. Geological Survey to the cross-bedded sandstone near Lyons, Colorado, 

 which has been quarried extensively — that is, to the upper 100 feet of the rocks 

 formerly called Lyons. The upper sandstone was found to overlap older for- 

 mations and to be closely associated with rocks containing invertebrates believed 

 to be of Permian age. These invertebrates are found in many places in lime- 

 stone stratigraphically above the Lyons sandstone^ — that is, in the lower part 

 of the Lykirfs formation. The Lyons sandstone as restricted is structurally 

 more closely associated with the Lykins formation of probable Permian age 

 than with the underlying Ingleside formation, of Pennsylvanian age, and is 

 therefore regarded as Permian. 



SYSTEMATIC DESCRIPTION OF GENERA AND SPECIES 



The best preserved and most characteristic of the fossil footprints 

 collected from the Hermit Trail are described in the following pages. 

 The list of described forms might have been lengthened had it seemed 

 wise to include all of the various kinds of imprints found, but in 

 several instances the evidence was so meager as to deter one from the 

 adoption of such a course. The possibility of acquiring still further 

 material from this locality in the immediate future made it injudicious 

 to describe tracks of which only a few imprints are known. 



This study has resulted in the founding of a considerable number 

 of new genera and species representing the only adequate Permian 

 Ichnite fauna known from North America. Its chief value, however, 

 is in recording a fauna which, as previously stated, may, in the ab- 

 sence of other fossil criteria, be of value in geological correlation. 

 It has not been possible to place, with assurance, more than one 

 or two of these newly described forms in a definite class. In a few 

 instances suggestions are made as to the animal to which certain 

 of the tracks may be attributed, but there now seems no possibility 

 of definitely connecting them. Should there eventually be found a 

 way of uniting the two lines of evidence, it is hoped that these tracks 



^ Henderson, Junius, Journ. Geol., Vol. 32, No. 3, 1924, p. 227. 



