io8 WHITMAN CROSS 



regularly oval, others obliquely pointed at one end. Notwithstanding their great 

 abundance no separation of the two valves was discernable. Remains of this 

 species occur profusely with Estheria ovata in the rocks of the Newark formation 

 of Virginia and North Carolina. 



ORDER PHYLLOPODA 



Estheria ovata Lea 



The specimens of Estheria are of different sizes, but all agree with the char- 

 acters of this species where they are distinctly recognizable. The valves are 

 rather strongly convex, slope forward from the umbo, and are prolonged on the 

 ventral side posteriorly. Average specimens measure 4™™ in length and 3™™ in 

 height (t^6 X J inch). Some specimens show considerable resemblance to ii5//ima 

 minuta var. brodieana Jones, but lack the greater development of the valves 

 anteriorly, and their lesser development posteriorly. 



This species is abundant in the Newark formation of the Atlantic border. 



The fossil fishes of the Kanab section undoubtedly occur some 

 hundreds of feet above the Shinarump conglomerate, but in view of 

 the present meager knowledge of that fauna, and considering the 

 character of the invertebrates, as identified by Dr. Shimer, as well 

 as the stratigraphic relations of the section, it would manifestly be 

 premature to accept at this time the qualified suggestion of Doctor 

 Eastman and refer the fish-bearing strata and the higher beds of the 

 Kanab section, including the Vermilion Cliff sandstone, to the lower 

 Jurassic. 



While Walcott found no fossils except silicified wood in the Shina- 

 rump conglomerate, there is evidence that a Triassic reptilian fauna 

 occurs locally at least in that bed or near it. This has been established 

 by the investigations of Ward, soon to be considered. 



Button's treatment of the Shinarump in 1882. — In his monograph 

 on the Grand Canyon district (7) Dutton accepts the reference 

 of the strata between the Shinarump conglomerate and the Aubrey to 

 the Permian, in accordance with Walcott's Kanab section. From 

 his general treatment of the subject it now becomes clear that the 

 description of the Shinarump Group given in the Geology of the 

 High Plateaus, and especially the references to its wonderful coloring 

 and constancy of character apply most particularly to the Permian 

 portion, for that is the part best exposed in the "Permian Terrace," 

 as Dutton still calls the one floored by the Shinarump conglomerate. 

 The inconvenience caused by the distribution of this conglomerate, 



