rLLUMs.] THE MISSOURI GEOLOGICAL SURVEY. 169 



The name " Ste. Genevieve limestone" is proposed for the second 

 Archimedes limestone (h') of the table (p. 293). 



The "third Archimedes limestone" (li") is the "second Archimedes" 

 or " Warsaw limestone v of HalPs section (p. 294). 



The classification of the formations between the top of the Encrini- 

 tal limestone and the base of the Coal Measures into a distinct group 

 under the name "Archimedes group" is worthy of particular notice. 

 Although the author made little account of it, and as far as I have 

 ascertained no further notice has been taken of it, recent studies have 

 convinced me that the primary subdivision of the Mississippian series, 

 based upon affinity and difference in the faunas, calls for a line of 

 demarcation at the place here indicated. The faunas of the Chester, 

 St. Louis, and most of those referred to the Warsaw formations are pale- 

 on tologically more closely allied than they are to the faunas of the Keo- 

 kuk and Burlington — i. e., the Encrinital of the Missouri geologists — 

 and considering the variations in the lithologic characters of these for- 

 mations in different parts of the Mississippi province I believe the 

 division of the Mississippian series into three groups defined upon 

 paleontologic grounds will greatly facilitate the understanding of the 

 relations of the various formations, whose differentiation hitherto has 

 been made upon lithologic character. This will avoid the necessity, as 

 the finer details of the geology are developed, of forced correlation with 

 already named formations, which is the only alternative to proposing 

 new names where the local stratigraphy is dissimilar to that of the typ- 

 ical section* 



For the uppermost of these groups, which is that called Archimedes 

 group by Dr. Shumard, I would propose the name Genevieve group, as 

 it was first defined in the county of Ste. Genevieve, by Shumard, and 

 along the eastern border of this county is well represented, as is shown 

 in Shumard's Report. 1 



To apply this classification I propose the following scheme, which 

 expresses the subdivisions into groups indicated by the fossil faunas 

 of the Mississippian series: 



C Chester. 

 Genevieve group.. . •? St. Louis. 



( Warsaw (in part). 

 n \ Keokuk. 



Mississippian series. < usage group \ Burlington. 



C Chouteau limestone and the "Vermic- 

 n . , J ular" and "Lithographic" formations 



Chouteau group .. . . < as propo8ed by G> c . Broadhead in the 



[ following report : 



In 1874 Mr. G. C. Broadhead published a detailed report of surveys 

 made by him as State geologist during the years 1873 and 1874. 2 



•Geol. Surv. Missouri, 1855-71, pp. 292-294. 



'Report of the Geological Survey of the State of Missouri, including field work of 1873-'74, with 

 91 illustrations and an atlas, hy Garland C. Broadhead, State Geologist. Printed hy the authority and 

 under the direction of the Bureau of Geology and Mines. Jefferson City, 1874 (pp. 734 and index). 



