NO. 3 



GRAND CANYON FOSSIL FOOTPRINTS — GILMORE 



33 



drag. Longer axes of feet impressions placed slightly diagonal to 

 direction of movement, alternating. Feet apparently unidactyl. 

 Genotype. — Triavcstigia niningeri n. sp. 



TRIAVESTIGIA NININGERI, new species 



Plate 10, fig. I 



Type. — Catalogue number 11.510, U. S. N. M. Consists of a slab 

 about 260 mm. long, having a trail traversing about two-thirds of 

 its length. 



1,0 

 '/. ^ 

 'L / 

 •', " 

 'I / 



F"iG. 14. — Triavcstiyiit iiiu'uujcri. Type. No. 11,510, U. S. N. I\I. 

 Diagram of trackway. About j natural size. 



Type locality. — Hermit Trail, Hermit Basin, Grand Canyon Na- 

 tional Park, Arizona. 



Geological occurrence. — Coconino sandstone (a loose slab from 

 hillside about 100 feet above the base), Permian. 



Description. — The trail here described consists of three parallel 

 rows of impressions, between two of which the intermittent drag of 

 a tail is faintly but clearly recorded. Width of the trackway 14 mm., 

 width of the paired rows 8.5 mm. Length of step is about 7.5 mm. 

 The feet seem to have been unidactylus, and made single mark-like 

 depressions that stand diagonal to the axis of the line of movement. 

 Curiously enough all of the markings forming the three rows have 



