NO. 3 GRAND CANYON FOSSIL FOOTPRINTS — GILMORE I9 



ity of the stride and by the pairing of the impressions made by the 

 fore- and hindfeet, the former ahvays being placed in front of the 

 latter. One trackway (No. 11,494 U. S. N. M.) among a considerable 

 number collected in 1926 deserves special mention because of the 

 unusual length of the median toes of the forefeet. These toes con- 

 siderably exceed in length the longest toes of the hindfoot (see fig. 6) 

 whereas the opposite condition usually prevails. Furthermore, in this 

 specimen the fore and hind tracks are subequal in size whereas the 

 forefoot impression is usually smaller. None of the pes tracks gives 

 indication of the jjresence of a fifth digit. The rather meager evidence 

 of its presence in the hindfoot may, however, now be considered as 

 absolutely established by two specimens (Nos. 11,491 and 11,512 

 U. S. N. M.) both of which show several pes tracks with five toes 

 clearly registered. 



Genus BARYPODUS Gilmore 



Barypodus Gilmore, Charles \V., Smithsonian Misc. Coll., Vol. jj, No. 9, 1926, 

 p. 27. 



The genus Barypodus was originally characterized on rather scanty 

 materials so that with the discovery of other species referable to this 

 genus, it now becomes necessary to emend the original definition as 

 follows : 



Generic characters. — Quadrupedal, plantigrade with three parallel 

 digits in both manus and pes. Digits long, either slender or stout, 

 well separated, and with or without webbing between the toes. Sole 

 of pes subtriangular in outline with heel hooking outward. Sole as 

 long as or longer than digits. Forefoot placed in front of hind. 



Genotype. — Barypodus paliiiatus Gilmore. 



KEY TO. SPECIES 



Large size. Toes long, slender, joined by web. Outer toe of manus 

 one-half length of inner. Palm of manus longer than digits with out- 

 ward hook of heel. 



B. palmatus 



Medium size. Toes long, slender, without webbing. Outer toe of manus 

 longer than inner. Palm of manus longer than digits with decided 

 outward hook of heel. 



B. tridactylua 

 Medium size. Toes, moderate length, stout without webbing. Outer toe 

 subequal in length with inner. Palm of manus apparently shorter than 

 digits, without outward hook. 



B. metszeri 



