130 B. SHIMEK 



Bluffs during the past summer and autumn. It had been pur- 

 posed to make a detailed comparative study of the fossil and 

 modern molluscan faunas of that vicinity, but the work was some- 

 what interrupted by the severe September rainstorms and Novem- 

 ber blizzards. Nevertheless interesting and valuable data were 

 obtained, and are here briefly presented. 



More than four thousand fossils were collected, and their 

 distribution was carefully noted in twenty exposures, beginning 

 at the eastern extremity of I 5th avenue in Council Bluffs, thence 

 along the bluffs to the High School, a distance of about one mile, 

 and in Fairmount Park, along its winding roads, for about half a 

 mile eastward. The location of the several exposures is shown 

 on the accompanying map. A list of the fossil species, together 

 with the number of specimens collected in each exposure, is 

 given in the appended table. If this table is studied it will be 

 observed that of the thirty species collected not one is aquatic. 

 For purposes of comparison the writer made collections of recent 

 shells in seven distinct localities in practically the region con- 

 taining the above-noted exposures. These localities are here 

 discussed in detail, the letters designating them being also 

 employed to mark them on the map. 



a. A grassy, treeless hillside in Fairmount Park nearly oppo- 

 site 11th avenue, and at an altitude of from 175 to 245 feet 

 above the river valley. 1 Species 8, 11, and 2g 2 were found 

 living. 



b. A grassy, treeless slope just above the exposure marked 

 N. Altitude about 200 feet. Species 8, 10, II, I5,and29 were 

 found. 



c. Near the 10th avenue entrance to Fairmount Park, at an 

 altitude of about 90 feet above the river plain, species 8, 10, 11, 

 21, 22, 27, and 30 were found. A few stunted and scattered 

 bur oaks grow on the slope immediately above this point. 



d. A brush-covered hill just above the exposure marked E. 



1 The altitudes were all determined by barometric measurements taken from the 

 nearest north and south street on the river flat. 



2 The numbers refer to the species named in the table of fossils. 



