NO. 3 GRAND CANYON FOSSIL FOOTPRINTS GILMORE I 5 



N. quadratus Matthew * quite certainly belongs in the genus Droiuil- 

 lopus with which its small size, digital formula of 4 and 4, and gen- 

 eral arrangement and relative length of toes are in full accord. For 

 these reasons it is unhesitatingly transferred to this genus to be 

 known hereafter as Dromillopus quadratus (Matthew). 



Unfortunately the case of A^. obfusis cannot be so satisfactorily 

 settled. The impression of the hindfoot offers no difficulties to its 

 assignment to Dromillopus but the forefoot shows only three toes 

 and the foot as a whole (see fig. 4) is quite out of accord with any 

 described Carboniferous ichnite. This is probably due to distortion, 

 as pointed out by Matthew," so that the number of digits and the form 

 of the foot as shown in figure 4 is probably not to be depended upon 

 as expressing the true characters of the normal manus imprint. For 

 that reason and as a temporary expedient this species is provisionally 

 assigned to the genus Dromillopus to be known as D ? obtusis ( Mat- 

 thew) until such time as the discovery of better preserved specimens 

 shall disclose its true generic affinities. 



NANOPUS MERRIAMI Gilmore 



Plate 4, fig. I 



Nanopus merriami Gilmore, Charles W., Smithsonian Misc. Coll., Vol. yy. 

 No. 9, 1926, pp. 9-12, pi. 4, fig. 2, text fig. 5. 



A specimen of Nanopus merriami (No. 11. 516. D. S. N. M.) is of 

 interest as recording a second occurrence of this species in the lowest 

 track-bearing level of the Coconino formation a considerable distance 

 north of where the type specimen was collected. It was found in situ 

 about 30 feet above the Coconino-Hermit contact, immediately above 

 the spring which supplies water for the trail caretaker's house in 

 Hermit Basin. It would now seem that this species is confined to the 

 lowermost horizon of the Coconino as no tracks attributable to it 

 have been observed in the upper levels. 



NANOPUS MAXIMUS, new species 

 Plate 3 



Type. — Catalogue number 11.506, U. S. N. M. A large slab of 

 light-colored fine-grained sandstone on which is an irregular track- 

 way showing impressions of all four feet. 



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

 tional Park, Arizona. 



* Free. Trans. Roy. Soc. Canada, Vol. 10, 1904. p. 98. 

 = Ofy. cit., p. 98. 



