NO. 3 GRAND CANYON FOSSIL FOOTPRINTS — GILMORE 53 



having bifurcated ends with inner branch longer than outer (see 

 fig. 25). These have suggested resemblance to the bifurcated digits 

 of the living Rliacoplionts maxinnis, a tree frog of Sumatra, which 

 has the unguals split to give better support to the terminal disks. 

 This reference should not convey the idea of relationship but simply 

 calls attention to an interesting similarity of structure. Sole narrow 

 antero-posteriorly but wide transversely. Digits have the following 

 lengths. I = 7.3 mm., II = 17 mm.. Ill = 22^ mm., IV = 30 mm., 

 V = 13 mm. Forefoot: Length about 32 mm., width 31.2 mm. Five 

 digits as in the pes, which grow progressively longer toward the out- 

 side, the fourth being the longest. The fifth shorter than the first 

 and especially set oiif from the other toes as in the hindfoot. All of 

 the toes seem to l)e terminated by pellets. None of the imprints show 

 bifurcated toes.. ¥\vst toe more widely separated from the others 

 than in the hindfoot. The digits have the following lengths : 

 I = 10 mm., II = 14.5 mm., Ill = 17.5 mm., IV = 20 mm., V = 

 9 mm. These tracks may be classed as digitigrade, as shown by the 

 extreme shortness of the sole impression. They were evidently made 

 by a quadrupedal batrachian, evidently of the walking type as indi- 

 cated by the alternating position of the steps of opposite sides. 



In such features as the digital formula, and their radiating arrange- 

 ment, these tracks bear a close resemblance to Hylopiis found in these 

 same beds, but the longer and more slender toes terminated either by 

 pellets or bifurcated ends at once distinguish them from that genus 

 as well as all others coming under my observation. It is therefore 

 regarded as new, the specific name hifurcatus being in reference to 

 the divided ends of a few of the toes on the hindfeet. 



Only one specimen referable to this species was found in the col- 

 lection of 1926. 



Genus PARABAROPUS, new genus 



The discovery of additional specimens that appear to be referable 

 to Lull's species Mcgapecia ? coloradcnsis ' indicates the necessity of 

 establishing a new genus for its rece])tion. Its original assignment to 

 the Nova Scotian genus Megapesia was regarded by Lull as pro- 

 visional, largely on account of the paucity of the materials at his 

 command. Cerfain resemblances to the genus Baropus suggest the 

 name Parabaropus, which may be characterized as follows : 



Generic characters. — Quadrupedal, ])lantigrade, with five digits in 

 both manus and pes. Forefoot smaller than hind ; toes in both rela- 



'Amer. Journ. Sci., V^ol. 45, 1918, p. 341. 



