abi by, KANSAS ACADEMY OF SCIENCE. 
Associated with the sandstones are white, yellow, buff, or bluish-colored 
shales and clays, the geological position of which is still a matter of uncertainty 
to me. I have been at a loss to know just how much of these belong to the 
Mentor. 
So far as I have been able to determine, the thickness of the strata varies 
from a few inches to 70 or 80 feet, and in a few instances the Dakota appears to 
rest directly upon the Permian, with no trace of Mentor or Kiowa. 
It appears to lie altogether between the altitude lines of 1,200 and 1,400 feet, 
and rests in part conformably upon the Kiowa, and in part unconformably upon 
the Permian. According to Professor Cragin, the following species of mollusks 
are found in the Mentor: 
t 
Ostrea franklini Coq. O. quadruplicata Shum. 
Anomia sp. Avicula salinaensis White. 
Gervillia mudgeana White. Modiola pedernalis Roem. 
Barbatia parallela Mk. Trigonarca salinaensis Mk. 
Nucula catherina Crag. Yoldia microdonta Mk. 
Trigonia clavigera Crag. Crastellina oblonga Mk. 
Lucina? sp. Cardium kansasense Mk. 
Protocardium texanum Conr. Corbicula nucalis Mk. 
Corbicula subtrigonalis Mk. Cyprimeria texana Roem. 
Tellina subscitula Mk. Arcopogella mactroides Mk. 
Leptosolen conradi Mk. Mactra siouxensis M. & H. 
Margarita mudgeana Mk. Turritella seriatim-granulata R. 
Sphenodiscus pedernalis VonB. 
Of these I have verified the most, and have a few that I have not certainly 
determined that may complete the list. 
A comparison of the species found in the Kiowa shales with the Mentor reveals 
several species common to both, which seems to indicate a close relationship. In 
Walnut and Greeley townships, Saline county, the Mentor is found resting con- 
formably upon what I take to be the Kiowa of Professor Cragin, and an interest- 
ing gradation is noticeable. The grayish calcareous shale of the Kiowa gradually 
changes to a dark reddish brown as it approaches the contact with the Mentor 
and appears to merge into it. A specimen of fossiliferous Mentor was obtained 
less than three feet above the Kiowa. 
On the other hand, the stone bearing the fossils strongly resembles the Dakota, 
in some instances appearing nearly identical with some of the leaf-bearing sand- 
stone. In one instance I found imperfect leaf impressions and fossil wood less 
than 50 feet above the Mentor on the same hill, and the sandstone intervening 
showed scarcely any change in general appearance. 
Briefly summed up, then, it seems that in the character of its sandstone and 
some of the associated shales the Mentor strikingly resembles the Dakota. But 
with respect to its fossils it resembles the Kiowa and Denison groups of the Co- 
manche. In conclusion, I will say that I do not wish to advance any theories. I 
have done some theorizing for my own gratification, but feel that my limited ex- 
perience in geological work would not warrant me in making these public, at least 
until I have studied the matter more thoroughly. I will, however, venture a ques- 
tion: Is it not possible that the difference in conditions, of temperature, depth of 
water, character of sea bottom and adjacent shores may have been sufficient to 
account for the variation in species from the Kiowa, even though they were co- 
temporaneous ? 
