Mineralogy and Geology. 429 
ductus called P. Calhounianus by Professor Swallow; very similar to 
_ some varieties of P. semireticulatus, but thought by Prof. S., to present 
_ well marked internal differences. There is likewise added in 16, a large 
Allorisma and a Spiriger similar to S. subtilita, but much more gibbous ; 
and in 14, Discinia tenuilineatus together with apparently the same Mo- 
notis, so often mentioned below. In 12, we also have added a small 
Spirifer similar to S. lineatus, but perhaps more nearly allied to the 
Permian species Martinia Clannyana, King. 
n passing into the next division above, No, 10, we find we have lost 
sight of all the characteristic Carboniferous forms, unless the Spirigera 
mentioned in some of the beds below be regarded as only a variety of S. 
subtilita, from which however, we think it specifically distinct; for with 
this exception, nearly all the fossils seen by us in this division, are such 
48 would be regarded as Permian types. Although the number of species 
found by us in No. 10 is not great, individual specimens are often nu- 
merous. Above this horizon we saw no more fossils through a great 
thickness of various colored clays, claystones, &c., until ascending to the 
Cretaceous sandstones crowning Smoky Hills. : 
we do not admit the existence in this region of an intermediate 
gtoup of rocks, connecting by slight gradations the Permian above, with 
the coal measures below, and must draw’a line somewhere, below which 
ous to the strata containing Permian types, however, is so gradual here, 
at it seems to us no ok undertaking to classify these rocks without 
classification adopted in the old world, would have 
Separated them into distinct systems, either upon lithological or palzeonto- 
logical grounds, especially as they are not, so far as our knowledge ex- 
tends, separated by any discordance of stratification, oF other physical 
break.* Indeed the fact that some of the Permian types occurnng in 
No. 10, were first introduced in beds below this, containing many Car- 
boniferous species, would seem to indicate that even No. 10 may possib! 
have been deposited just before the close of a tran 
the conditions of the Carboniferous, to those of the Permian epoc 
“ fi > 
impossible, with our present information, to determine with wn om 
Upper limits of the series containing Permian forms. It is true, there is 
ist of Ili- 
* We ha i by Dr. J. G. Norwood, former State Geologist o 
ws ae bs cet Md Pad te amp 
the Kansas Permian rest. unconforma 
: strata 
. — j ld of course, not only 
until after the. close of the Cretaceous era, which Wer’ oe dip at tbe 
