20 PROCEEDINGS OF THE ACADEMY OF 



cylindrica, of the slender variety so common in the Coal measures of Kansas 

 and Missouri, was not seen above 22; nor was any species or variety of 

 that genus observed above this horizon. 



Apparently, the same species of Monotis, mentioned at various horizons far 

 beneath, were occasionally met with in 30, 25, 23, and 20, generally associated 

 with the same species of Synocladia, ranging far down into the upper Coal 

 measures. In division No. 19, we again met with the Synocladia biserialis, and 

 a Spirigera allied to S. subtilita, if not identical, along with a new species of 

 Chonetes we have called C. murcronata, which ranges down into the beds near 

 the base of the section. Along with these, were also Productus N~orwoodi, and 

 Orthisina, Shumardiana, both of which are common in the Coal measures far 

 below, and a large Orthisina similar to 0. umbraculum, but apparently more 

 findy striate. 



Ascending through the intermediate beds to No. 12, we continue to meet with 

 nearly all the species mentioned in 19, with the exception of Chonetes mucronata. 

 We also have, first in 18, a large species of Productus, 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, hut much 

 more gibbous ; and in 14, Distina tenuilineatus, together with apparently the 

 same Monotis, 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. 



The succeeding bed above, No. 11, appears also to contain a mingling 

 of Permian with Coal measure forms, for we have in it the following Permian 

 types, viz.: My aim a very similar to M. Squamosa, Pleurophorus ? subcuneata, 

 Bakevellia parva and Monotis Haumi along with a Euomplialus near E. rugosus, 

 the same gibbous Spirigera, similar to S. subtilita, Orthisina umbraculum? and 

 O. Shumardiana. 



On 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 as would be regarded as Permian 

 types. Although the number of species found by us in No. 10 is not great, 

 individual specimens are often numerous. Above this horizon we saw no more 

 fossils through a great thickness of various colored clays, claystoues, &c, until 

 ascending to the Cretaceous sandstones crowning the Smoky Hills. 



If we do not admit the existence in this region of an intermediate group of 

 rocks, connecting by slight gradations the Permian above, with the Coal meas- 

 ures below, and must draw a line somewhere, below which all is to be regarded 

 as Carboniferous, and all above as Permian, we should certainly, upon palae- 

 ontological principles alone, carry this line up as far as the top of division 

 No. 11. The passage from the Carboniferous to the strata, containing Per- 

 mian types, however, is so gradual here, that it seems to us no one, under- 

 taking to classify these rocks without any knowledge of the classification 

 adopted in the old world, would have separated them into distinct systems, 

 either upon lithological or palaeontological grounds, especially as they are not, 

 so far as our knowledge extends, separated by any discordance of stratifica- 

 tion, or other physical break.* Indeed the fact that some of the Permian types 

 occurring in No. 10, were first introduced in beds below this, containing many 

 Carboniferous species, would seem to indicate that even No. 10, may possibly 



* We have been informed by Dr. J. G. Norwood, former State Geologist of Illinois, 

 that the rocks in that State, referred by him and others to the same epoch as the Kansas 

 Permian beds, rest unconformably upon the Coal measures. This, however, would be 

 impossible in Kansas, since no disturbances of the strata occurred there, until after the 

 close of the Cretaceous era, which would, of course, not only cause the Cretaceous and 

 Carboniferous, but all intermediate beds, to dip at the same angle. 



[Jan. 



