NO. 3 GRAND CANYON FOSSIL FOOXrRINTS — GILMORE I7 



preserved one (see A, fig. 5) it is relatively short fore and aft. The 

 outer toe is somewhat set off from the median one. Sole broadly 

 rounded behind. Judging- from the depth of the imprints the weight 

 of the animal was largely carried by the hind limbs. The length of 

 digits in the manus varies so much in the different imprints that it 

 seems useless to record their measurements. The outline of the manus 

 as given in figure 5. A. is made from the best preserved imprint on 

 the slab, but the relative length of toes is subject to revision when 

 better specimens are found. 



The presence of three and four digits in the manus and pes, 

 parallel arrangement of the two middle toes of the hindfoot, short, 

 broadly rounded sole, and forefoot placed in front of hindfoot, are 

 characters found in the genus Xaiiof'us. 



The large size of Nanopus maxiinus at once distinguishes it from 

 the other species of the genus, all of which are small. From A", mcr- 

 rianii from this same formation, but apparently restricted to the 

 lower part of the track-bearing horizon, it may be distinguished not 

 only by its much greater size, but also by having the two lateral toes 

 of the pes subequal in length with the two median toes, whereas in 

 both N. caudatus Marsh and N . mcrriami Gilmore the two lateral 

 digits are shorter than the median. From N. caudatus it is further 

 distinguished by the more slender and acuminate form of the digits 

 as contrasted with the heavy rounded toes of that species. The specific 

 name is suggested by its great size as contrasted with the smaller 

 footprints of the other species of the genus. 



Genus LAOPORUS Luir 



Laoporus Lull, R. S., Amer. Journ. Sci., \'ol. 45, 1918, p. 339. 



Generic characters (emended). — Quadrupedal, semiplantigrade, 

 with four digits in manus and five in the pes; fifth toe often not 

 impressing. Lateral digits always shorter than median pairs. Sole 

 broad, digits usually short. F'eet usually grouped in pairs with front 

 foot always placed in front of hind. 



\\fter the manuscript of the present paper had been accepted f(ir publi- 

 cation an article on British Permian Footprints by George Hickling (Man- 

 chester Lit. and Pbilos. Soc, Memoirs, Vol. 53, 1909, Art. 22, pp. 1-24, 

 pis. I to IV) came to my attention for the first time. Although too late to 

 be discussed in the present article, I wish in this note to call attention to 

 the fact that many of the British tracks show striking resemblances to 

 those of the Coconino and that the genus Laoporus is quite certainly represented 

 in the Pernith Red sandstone; see figs. 10 and 11, pi. II, of the article cited. 



This brief note will bring to the attention of those interested the above 

 mentioned fauna, and a more complete discussion of it will be included in 

 my next publication dealing with footprints of the Grand Canyon. 



