NO. 8 GRAND CAN VOX FOSSIL FOOTTRINTS GILMORE 5 



the specimen representing a distinct species, but more perfectly pre- 

 served material is needed to determine that i)oint. The trackway 

 shows two parallel lines of imprints arranged as in the type in groups 

 of four, the groups of the two sides alternating. These groups have 

 the usual arrangement of a row of three regularly spaced tracks with 

 the fourth offset inward. 



After a study of the type specimen, it was my conclusion that the 

 trackway was probably made by some Permian crustacean. In con- 

 firmation of the probable correctness of that conclusion, Mr. Reming- 

 ton Kellogg, of the U. S. Biological Survey, calls my attention to a 

 considerable similarity between these tracks and trails made by the 

 living sand crab Ocypoda albicaiis, recently observed b)- him in the 

 sands on Hatteras Island. Xorth Carolina. 



ICHXTTES I-■RO^r THE llICR^riT FORMATION 



Genus HYLOIDICHNUS Gilmoie 



Hyloidiclmus Gilniore. Charles W., Smithsonian Misc. Coll.. ^'ol. 80, No. 3. 

 1927, p. 51. 



Generic characters.- — Quadrupedal, semi-digitigrade. Both manus 

 and pes have five digits. Manus smaller than pes and placed in front 

 of hindfoot. Toes either terminated v^ith pellets or having bifur- 

 cated ends. 



• HYLOIDICHNUS WHITEI, new species 

 Plate 3, fig. I 



Type. — Catalogue number 11,692, IJ. S. X. AI. Consists of a small 

 slab on which are four imprints. Collected by Dr. David White, 

 June, 1927. 



Type locality. — Yaki Trail ( " Cedar Ridge " 500 feet west of trail). 

 Grand Canyon X'ational Park. Arizona. 



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

 contact, Permian. 



Description. — Stride estimated to be al;out 106 mm., width of 

 trackway about 45 mm. Forefoot slightly smaller than hind and 

 placed almost directly in front of it. Hindfoot: Length about 24 mm., 

 width about 22 mm. live toes. The toes are long and especially 

 slender, fourth longest, others growing progressively shorter toward 

 the inside of the foot. First only faintly impressed, but apparently 

 about the same length as the fifth. Digits II to V having terminations 

 slightly enlai-ged, the first apparently having bifurcated ends. The 

 toes have the following lengths: 1 = 7-5 """n-, II = ii.i mm.. 



