The Ecology of a Sheltered Clay Bank 183 
Rach of these cells, or pockets, contained an egg attached 
to a small pellet of yellow pollen. 
At first I thought that it was always the head of the 
male which plugged the doorway; but as I later learned 
that each burrow was really an apartment-house occupied 
by many adults, I have been in doubt whether the one at 
the door may not have been one of the feminine oceu- 
pants. This common passage way is larger underground 
than is the doorway, which is just wide enough to admit 
one bee at a time. One nest which I opened had a 
tunnel in the hard yellow clay nine inches long and three- 
sixteenths of an inch wide, excepting at the narrow en- 
trance. Pockets on either side of this tunnel had young 
in all stages of development, from minute creatures cling- 
ing to a little ball of pollen, to pupae already deeply pig- 
mented. Besides these there were a half-dozen adults, 
possibly mothers or adult sisters. After the nest had 
been dug up, eight bees returning home congregated 
before the ruins. The adults as they emerge nidify 
in the same tunnel and gradually extend it. While these 
are solitary bees they are very neighborly, and this 
habit of community dwellings seems to point in the di- 
rection of socialization. Indeed it almost seems to be 
a link between the solitary and the social habit of bees. 
Near the end of the season, October 2, 1920, and 
again September 28, 1922, at Wickes, Mo., I witnessed a 
new phase in the life of this species. Thousands of 
these little bees were executing a sun-dance on the sunny 
hilltop, where the grass was closely mowed. They were 
in a great many groups of a few bees to several hun- 
dred, while a few groups had several thousand. Some 
groups were close together and some isolated, some dane- 
ing over the short grass and others over the barren olay 
