350 Schxclwrl — Carboniferous of Grand Canyon of Arizona. 



of sands had been deposited, the area subsided, then 

 another zone of sand was laid over it, and finally the 

 entire area and a great deal more went beneath the sea, 

 for over all of the Coconino lies a typical shallow-water 

 marine deposit, the Kaibab dolomite. 



At about 150 feet above the base of the Coconino sand- 

 stone, in a bend on the Hermit trail, in the quarried mate- 



FlG. 1. ' 



Fig. 1. Upper part of Grand Canyon, Arizona, as seen from Mohave Point. 

 I, Kaibab limestone; II, Coconino sandstone; III, upper part of Supai forma- 

 tion, red shales; IV, lower part or Supai formation proper. 



rial of the trail cutting, were collected amphibian tracks 

 of small animals that travelled up and down the Preset- 

 ting slopes. They were not seen on the very limited sur- 

 faces of the horizontal planes. These Professor Lull is 

 describing in this number of the Journal as Laoporus 

 schucherti and L. noblei. He regards them as ancestral 

 amphibia of the group Protopoda. No other organic 

 remains are known from the Coconino formation, and 

 the cause is probably to be sought in the originally loose 

 and repeatedly reworked sands, a most unfavorable hab- 

 itat for animals. The conclusion as to the origin of this 



