52 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 80 



HYLOIDICHNUS BIFURCATUS. new species 

 Plate 16 



Type. — Catalogue number 11,518, U. S. N. M. Consists of the 

 obverse slab on which is a trackway about 500 mm. in extent. 



Type locality. — Hermit Trail, one-fourth mile west of sign " Red 

 Top " head of Hermit Gorge, Grand Canyon National Park, Arizona. 



Geological occurrence. — Hermit shale, 30 feet above Hermit-Supai 

 contact, Permian. 



Fig. 25. — Hyloidichnus bifurcatus. Type. No. 11,598, U. S. N. M. 

 Diagram of trackway. About j natural size. 



Description. — Stride abotit 180 mm. ; width of trackway about 

 125 mm. Forefoot somewhat smaller than hind and is placed in 

 front of it. Hindfoot: Length 42 mm., width 40.5 mm. There are 

 five toes, progressively longer toward the outside the fourth being 

 the longest. The fifth digit is much shortened, and somewhat set 

 off from the others. Fourth digit is more than twice the length of 

 the sole and extending directly forward as in Hylopiis. First and 

 fifth toes terminated by pellets, second, third and fourth usually 



