The Ecology of a Sheltered Clay Bank 181 
My earlier notes show that in 1917 there were only 
three of these upturning turrets, which indicated that 
this species was newly arrived then. As early as June 
18, 1921, I counted 40 such turrets, with A. rawi coming 
in and out. They were not scattered over the whole bank, 
but were distributed in groups; this probably means 
that the bees build very near to the spot where they are 
born. Fig. 10 shows a colony of 20 upturned turrets 
in a small area (for this picture a wad of cotton was - 
placed in each vertical chimney, to better distinguish 
them from their neighbors), and Fig. 6 shows a mother 
twice natural size. 
I accidently broke off the turret of one nest about an 
inch long, while it was in course of construction. The 
bee coming out with the next load of mud did not seem 
in the least surprised, but without turning about to ex- 
amine the condition, she placed her load at the base and 
began on a new turret. On June 18th ten new turrets 
Were just begun. 
The following record of one typical bee’s work gives 
an idea of the manner of making the turrets. This bee 
entered a shallow old hole and kicked out a small quan- 
tity of loose dust; after some minutes of this, she left 
and returned presumably with water. She then began 
to bring out loads of mud and started to make her turret. 
The face of the bank here was uneven and her first tine 
loads went to fill the depression, first above the orifice 
and then below it, until it was level and ready to re- 
ceive the chimney, which she continued in the same man- 
ner. A trip for water usually consumed two minutes. 
In leaving the nest for water she came out head first, 
having turned around in the tunnel; in coming out with 
mud, she always emerged backwards and applied her 
