138 B. SHIMEK 



EXPOSURE D 

 The shell stratum is not so rich in fossils as in C. Above it there are 

 15-20 feet of clay in which a few Succineas were found. In the clay below 

 the shell stratum there are several distinct but irregular bands of lime 

 nodules — some very large. 



EXPOSURE E 

 Very similar to D, but with only one band of nodules. 



EXPOSURE F 

 Fossils are very abundant in the shell stratum, which can here be traced 

 for 3 or 4 rods. The shell-less loess above is 8 or 10 feet thick. 



EXPOSURES G, H, I, /, and K 



These exposures were all formed from the same ridge by deep cutting 

 and grading. The shell stratum is distinct in all of them, and, as in all the 

 other sections, it follows in general the contour of the surface. It varies in 

 thickness here from 6 to 20 feet. It is by no means equally fossiliferous 

 throughout. 



EXPOSURES L and M 



These were formed by the grading of High School avenue. The street 

 slopes westward from the High School, and drops about 60 feet in a block. 



1 The nomenclature of Pilsbry and Johnson's recent Catalogue of the Land Shells of 

 North America is here employed. As there are some departures from former usage, 

 the changes are here noted : 



Species 2, 3, and 4 were formerly included under V. pulchello. 

 Species 5 and 6 were referred to the genus Mesodon, and 7 and 8 to Slenotrema. 

 Species 9 was included under Strobila labyrinthica. 

 The species of Leuchochila and Bifidaria were included in Pupa. 

 Species 18 was called Ferussacia subcylindrica. 



Vitrea, Comulus, and Zonitoides were formerly placed in the genus Zonites, and 

 No. 19 was called Zonites radiatulus. 

 Pyramidula was formerly Patula. 

 Species 29 was called S. lineata. 



2 One specimen of P. profunda was found by the writer in exposure C (since con- 

 siderably altered) in 1890. 



3 Three specimens of this species were collected in exposure C in 1890. 



*The writer formerly regarded this as a form of Zon. nitidus. Mr. Pilsbry, 

 however, regards it as distinct, and in deference to his opinion his name is retained. 



s The form of S. obliqua which occurs most commonly in the loess is the narrower, 

 smaller form, with more extended spire, such as is not uncommon (living) in Iowa and 

 as far east as Indiana. As it is difficult to distinguish between some forms of this and 

 S. grosvenorii, the two species are not here separated, as more time for careful com- 

 parison of the large sets will be required. 



