106 IOWA ACADEMY OF SCIENCES. 



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



Altitude about 170 feet. A small collection contain- 

 ing species 11 and 30 v^^as made. 



E. A locality in the northwestern part of Fairmount park, 



on a northerly slope, somewhat grassy, but witii 

 shrubs and a few Bur-oaks, nearly opposite Eighth 

 avenue. Altitude 280 to 300 feet above the valley. 

 Here we found species 3, 8, 11, 13, 18, 19 and 27, and 

 also one specimen of Bifidaria procera, the only recent 

 species found in the tract examined, which was not 

 found in the loess. This locality is just over the 

 brow, on the north or leeward side* of one of the 

 most exposed ridges in the area under consideration. 



F. A part of the same slope immediately below E, and 



fifty to 100 feet lower. Here the forest is better 

 developed and contains a number of species of trees. 

 Species H, 11, 18, 19, 22, 25 and 28 were found. 



The points E and 7*' are on the same very steep 

 slope, but E is much more exposed and drier, 7^ being 

 more protected by its forest covering and position. 

 A comparison of the species from these points is 

 therefore interesting. Species 3 and 13, while com- 

 mon at /:; were not found at F the lower point. While 

 18 was common at E, only one specimen was found 

 at F. Number 19 is also more common at E than at 

 F. These facts are of interest when we seek to 

 determine the extent to which shells are likely to be 

 washed down even very steep slopes. Numbers 8 

 and 11 were about equally abundant, while numbers 

 22, 25 and 28 were found only at F. 



G. The banks and grassy slope near and above the expos- 



ure M. This yielded species 3, 13, 21, 24 and 27. 



It will be observed that species 1, 3, 4, 5, 6, 7, 9, 12, 14, 15, 

 16, 17, 20, 23 and 26, — or just one-half the total number, — are 

 not contained in the collections of modern shells cited. The 

 number of individuals of the surface species is also compara- 

 tively small. Of these numbers, 1, 16 and 23 are extinct in that 

 section of the country, number 1 occurring eastward, number 

 16 westward, and number 23 being entirely extinct. 



The modern fauna of the more or less exposed hills at Coun- 

 cil Bluffs is much poorer in species and in specimens than the 



*The prevailing winds during the seasons of tlie year when the snails are active, 

 are from the southwest. 



