268 REPOET OF THE AMERICAN COMMITTEE. 
I am informed by Major Powell that the Shinarump series is 
that which I have referred, on account of its vertebrate fauna, 
to the Permian. It is therefore to be excluded from the Meso- 
zoic realm. Of the three remaining series the Vermilion Cljff 
is, to judge from the description, that which I referred to the 
upper or Keuper Trias in 1877 (Report Expl. Sur. W. of 100th 
Meridian, G. M. Wheeler, vol. iv.), while the two others are 
referable to the Jurassic. It is not unlikely that they are identi- 
cal with the two divisions into which King divides the Jurassic 
system of Nevada, and if so, the names of Powell take prece- 
dence of those of King. Until this identity is determined by 
direct tracing, or by paleontological comparison, their relations 
will remain uncertain. 
E. D. Cope. 
