246 University of Kansas Geological Survey. 
below them. I believe that this is due to shallower water and nearer 
shore lines. 
The recognition of the Pierre deposits within Kansas was first 
made by myself in 1891. I recognized then only the deposits on the 
North Fork of the Smoky Hill, which had previously been considered 
to be Niobrara. Vertebrate fossils from this locality had been col- 
lected by Mudge and Marsh, and it is not at all impossible that 
some of them have been described as Niobraran. I found in 1891 
two species of saurians at this place, both of which are different 
from any that I know below. Later a specimen of Clidastes, obtained 
by Mr. Sternberg from this same locality, was described by me. 
as C. Westii. Another species of Clidastes I have since seen from 
Colorado. So far this is the only genus of vertebrates from the 
Pierre that is known to occur in the Niobrara, though the turtle 
Arcalon of Wieland seem very closely allied to Protostega. The 
genus Mosasaurus of the Pierre is closely allied to Clidastes, yet 
sufficiently distinct to be separated. Tylosaurus is replaced by a 
peculiar genus, of which a brief description was given by myself in 
the Kansas University Quarterly, vol. I, p. 10. Further study shows 
that the genus is entitled to a generic name, for which I propose 
Brachysaurus. 
It can not yet be said that the Pierre deposits are conformable in 
Kansas with the Niobrara. Hay has recorded the beds from Butte 
Creek and the White Woman, but I believe that he is in error in 
hese references. He also recognized the beds in Cheyenne county 
as Fort Pierre,a determination confirmed by Mr. Logan in this Report. 
