NO. 3 GRAND CANYON FOSSIL FOOTPRINTS — GILMORE 55 



reliance was placed for the original association of the detached im- 

 prints, was found to have on its surface the tracks of no less than 

 four kinds of animals, all rather indistinctly recorded in so far as 

 their exact details are concerned. \one of these can be positively 

 identified with either of the detached tracks. The footprint which has 

 suggested resemblances to the pes track figured by Lull is much 

 smaller, but disregarding this difference in size, the preservation is 

 such as to render its positive identification with that track out of the 

 question. 



In front of this track are two smaller tracks, one slightly encroach- 

 ing upon the other, which in the light of newly discovered specimens 

 can quite certainly be identified as the manus and j^es tracks of 



Fig. 26. — Mcgapccia ? coloradensis LulJ. Type. No. 2,145, Tale 

 Museum, a, right manus, h, right pes. A natural size. (Reduced 

 from Lull.) 



Hyluidichnus bifurcatus. The other tracks present on this slab are 

 inferior in their preservation and deserve no further mention at this 

 time. 



After study of the type materials it is my conclusion that no evi- 

 dence exists for the association of these detached footprints and on 

 that account the track illustrated by Lull as the pes (see fig. 26) is 

 selected as the type of the species P. coloradensis. 



Comparison of the manus track of the newly discovered trackway 

 (see fig. 27) with the type of P. coloradensis (Lull) (see fig. 28) 

 shows such close_ resemblances between them as to leave no doubt 

 that the type track pertains to the manus rather than the pes as 

 originally determined. These tracks are practically of the same size, 

 as may be seen in the table of comparative measurements and further 

 resemblances are found in the short radiating digits, with rounded 



