6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 7/ 



may aid in bringing about a better understanding and interpretation 

 of the habits and characteristics of the animals that made them. 



Genus DOLICHOPODUS, new genus 



Generic characters. — Quadrupedal. Pes long and narrow. Fourth 

 digit long, slender, and curved outward. Three ( ?) toes in manus, 

 which is placed behind and outside tracks of the pes. Toes acumi- 

 nate, clawed, fifth digit of pes wanting. Feet turned strongly in- 

 ward toward line of movement. 



DOLICHOPODUS TETRADACTYLUS, new species 

 Plate 4, fig. I 



Type. — Catalogue number 11,123, U. S. N. ]\I. A slab carrying a 

 consecutive series of eight footprints. 



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

 tional Park, Arizona. 



Geological occurrence. — Coconino sandstone (150 feet above base), 

 Permian. 



Description. — Stride about 230 mm. ; width of trackway, 51 mm. 

 Hind foot: Four digits, fifth wanting, fourth long, slender, curved 

 outward. Three inner digits progressively shortened. All toes acu- 

 minate except possibly the first. Heel rounded. Length of track 

 ^2 mm., width 15 mm. Length of digit I, 4 mm.; digit H, 5 mm.; 

 digit HI, 7 mm.; digit IV, 16 mm. Forefoot: Three (?) parallel 

 digits, toes acuminate. Placed behind and outside hind foot. 



The selected type of this species is a consecutive series of eight 

 footprints divided equally between the fore- and hindfeet of the 

 right and left sides of an animal walking in a straight course. The 

 imprints made by the forefeet are so indistinct as to be visible only 

 by special lighting, &nd this, combined with the narrow trackway and 

 length of stride at first gave the impression that the track was made 

 by a bipedal animal. These front impressions fall behind and outside 

 of the deeper imprints of the hindfeet, and in an oblique light three 

 short parallel digits are clearly discernible, the outer two being of 

 equal length and sharply pointed. The inner toe is much shortened. 

 The toes of both feet are directed strongly inward toward the median 

 line of the trackway. 



The striking feature of the more deeply impressed tracks of the 

 hindfeet, which, by the way, are quite unlike any others yet found 

 at this locality, is the presence of a long, slender fourth digit ter- 

 minated by a sharp claw that curves outward. On the inner side 



