NO. 3 GRAND CANYON FOSSIL FOOTPRINTS — GILMORE 21 



smaller size of the digits and the indistinctness of the impressions 

 raises the question of these imprints having heen made by the pes, 

 but when critically examined, the fact that some of the impressions 

 were made upon the slightly raised flow of sand forced out by the sole 

 of the preceding foot, seems to leave no alternative conclusion than 

 that they were made by the pes. If this interpretation be correct, then 

 we have the very unusual condition of having the hindfoot apparently 

 bearing less of the weight of the animal, as evidenced by the shallow- 

 ness of the imprints. The sole is not distinctly impressed (see fig. 7) 

 in any of the tracks and on that account no idea of its shape, extent, 

 or peculiarities is to be gained from this specimen. Forefoot: Length 

 81 mm., width 46 mm. Three digits, long, parallel and sharply acumi- 

 nate. Toes directed straight forward in relation to axis of trackway. 

 Digit I is ^y mm. long, digit II, 43 mm., digit III, 42 mm. Sole sub- 

 rectangular with a blunt, hook-like protuberance on the outer poste- 

 rior angle as in B. paliiiatiis. There is no deviation of the lateral toes 

 as in so many three toed tracks, notably those of the Connecticut- 

 Triassic, but in both fore- and hindfeet the toes are placed nearly 

 parallel. All of the toes are equally well impressed. The resemblance 

 in form of the palm of the manus to B. palniatits seems to indicate 

 that the original interpretation of the position of the hook-like pro- 

 tuberance as being on the inside of the foot was in error. In the 

 specimen now before me it is clearly shown to be on the outer side. 

 This indicates that the type of B. palmafus belongs to the right side, 

 a fact that was indeterminable at the time of description, due to the 

 paucity of the type materials. 



Although there are many resemblances to be found in a comparison 

 of the two species here discussed, they may be at once distinguished 

 by the smaller size of B. tridactylus, the absence of webbing between 

 the toes, and the smaller relative size of the hindfoot as contrasted 

 with the fore. Differences found in the relative length of digit III 

 of the forefoot also furnish another distinguishing character. 



BARYPODUS METSZERI, new species 

 Plate 6 



Type. — Catalogue number 11,505, U. S. N. M. Consists of a track- 

 way about 560 mm. in length showing impressions of all four feet. 



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

 tional Park, Arizona. 



Geological occurrence. — Coconino sandstone (about 150 feet above 

 base), Permian. 



