352 C. S. PROSSER 



Chase formations zones occur in which there are numerous speci- 

 mens of a few species which belong to genera that in Europe are 

 regarded as of Permian age ; but inter-stratified with these zones 

 are others which contain numerous specimens of a considerable 

 number of the Missourian species. The writer has already 

 stated that "The Neosho and Chase formations are transitional 

 from the Upper Coal Measures to the Permian as first defined 

 by Murchison for Russia, and belong to the division which has 

 generally been called Permo-Carboniferous in this country. In 

 accordance with the views of the majority of present European 

 geologists familiar with this problem it is probably better to 

 include the Permo-Carboniferous rocks of Kansas in the Per- 

 mian series." 1 The base of the Neosho formation is about 50 

 feet higher than the base of Swallow's Lower Permian or Meek 

 and Hayden's Permo-Carboniferous ; and the top of the Chase 

 formation is, approximately, 90 feet higher than the base of 

 Meek and Hayden's Permian, or between 50 and 80 feet lower 

 than the top of Swallow's Lower Permian. The thickness of the 

 Neosho is 130 feet, 2 and that of the Chase 265 feet, 3 making a 

 total thickness of 395 feet. Mr. Beede, who is describing the 

 Carboniferous and Permian invertebrate faunas for the Univer- 

 sity Geological Survey of Kansas, writes me that " there is 

 ample evidence for placing the division line between the Coal 

 Measures and Permian where you have." 



Succeeding the Chase is the Marion formation, with a thick- 

 ness of from 300 to 400 feet. 4 The lower portion of the Marion 

 contains a fair Lamellibranch fauna which, however, decreases 

 until in its upper part very few species are found. The follow- 

 ing thirteen species and one variety have been found in this for- 

 mation, together with some other forms which as yet have only 

 been doubtfully identified either specifically or generically, viz. : 

 Aviculopecten occidentalis (Shum.) Meek, Bakevellia parva M. & 



'Jour. Geol., Vol. Ill, pp. 795, 796. 



2 Ibid., pp. 766, 799. 



3 Ibid., pp. 773, 798. 



4 Univ. Geol. Surv. Kans., Vol. II, p. 66. 



