IOWA ACADEMY OF SCIENCES.’ 
113 
Exposure D. The shell stratum is not so rich in fossils as in C. Above it 
there are fifteen or twenty 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 three or four rods. The shell-less loess above is eight 
or ten feet thick. 
Exposures G, H, I, J 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 other sections, it follows in general the contour 
of the surface. It varies in thickness here from six to twenty feet. It 
is by no means equally fossLliferous 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 sixty feet in a block. On the north side the shell stratum is 
nearly parallel to the street grade, and but little above it. On the 
south side it dips b dow the street about half-way down the slope. 
Exposures N, O, P, Q, B, S and T These are all exposures along the road 
which winds eastward from the Tenth avenue entrance to Fairmount 
park At N the road is about 1^5 feet above the river valley, and the 
shell stratum (which is here very rich in fossils), extends about three 
feet higher. It dips down toward the west at such an angle that it 
would connect with the shell stratum at E, which is about 100 feet 
lower. The same layer may be traced, more or less indistinctly, to O, 
where there is a cut about twenty feet deep. The shell stratum rises 
to about eight feet above the roadbed (here aboat 200 feet above the 
river valley), but fossils are not abundant. The remaining exposures 
along this road are formed by the road cutting the smaller lateral lobes 
of the greater ridges. The letters apply to the extent of road from 
bend to bend, not to individual exposures. At the southern bends in 
the road are the high points, the road sloping down to near the bases of 
the ridges to the north. Fossils are found ia most of the little expos- 
ures (which, in but few cases, exceed fifteen feet in height) along the 
road, but they are nowhere as abundant as in some of the exposures 
along the bluff fronts. The exposures which are represented on the 
map, but not lettered, are non-fossiliferous. 
THE IOWA LIVERWORTS. 
BY B. SHIMEK. 
Among the groups of plants hitherto neglected by Iowa 
botanists, the liverworts are by no means the least interesting. 
A few of the large thalloid species have long been familiar 
objects to botanists working in other fields, but the general 
lack of economic importance of the group, and the habits and 
small size of most of the species, no doubt account for the fact 
that they have attracted less attention than they deserve. 
In general, the liverworts prefer moist places. They may 
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