The Ecology of a Sheltered Clay Bank 159 
mec River empties into the Mississippi about one-third 
of a mile northeast of this point. This region is attrac- 
tive to fishermen and as a result about a dozen club- 
houses have been built near the station. Some of these 
cottages were built upon posts or stilts, thus exposing 
the earth beneath them. Two such houses were situated 
on a northward slope, but there was no perceptible life 
in the earth under them. This was probably due to their 
shaded condition and the friable nature of the earth 
there. In the construction of another of these houses, a 
quantity of clay had been excavated from the cellar and 
had been shoveled under the porch to save the expense of 
hauling it away. In the twelve years that this heap of 
subsoil had lain there, it had become packed to a very 
hard consistency. The house faced the east where it 
received the benefits of the morning sun. The porch was 
four to five feet above the ground, and thus admitted a 
flood of light in the morning and midday, but excluded all 
the afternoon sun, and afforded protection from the 
weather. This bank of hard-packed yellow clay was 
about eighteen feet long, and varied from thirty to thir- 
ty-six inches in height. The wood-boring inhabitants of 
the porch, the life in the clay bank, the insects among the 
rubbish on top, the occupants of the rambler-rose stems in 
front of the bank, and the occasional visitors all consti- 
tuted a legitimate biotic unit, the subject of this study. 
(See Fig, ie 
In May, 1917, when the unit was first discovered, it was 
noted that the northern half of the clay bank was riddled 
With holes, while the south half was not so, but at the 
extreme south end a few turrets of a wild bee were found. 
Figs. 3 and 4 show the south and the north half of 
the clay bank respectively, and the enormous amount of 
