172 Trans. Acad. Sci. of St. Louis 
quite drenched and made their elegant pubescence all 
sodden. 
The notable feature was that this species had again 
increased enormously. Their distribution over the face 
of the clay bank was interesting: at the extreme south 
end were 10 turrets, in the central part, 275, and at the 
extreme north end, 390, making a total of 675 in three 
rather distinct groups. Besides this, more than a hun- 
dred bees had nests with no turrets and during the week 
I saw about 75 more chimneys constructed. This may 
indicate that each mother may make more than one nest 
in a season.* Many of the bees were bringing in pollen, 
others were building, and yet many more than three- 
fourths were at this time coming in apparently empty- 
handed. I think that they moisten the pollen with nec- 
tar, and this would mean many trips which to an ob- 
server would appear empty. Then again each cell is 
varnished inside to a certain depth which gives it a 
smooth glossy finish. This is no doubt for the purpose 
of making the brood cup impervious to water; at least 
when one drops water on the inside from a pipette, 
the drops retain their shape, and if the entire cup is 
filled, it retains the water for a long time. On the con- 
trary, if a drop be placed on the outside of the cell, it 
immediately spreads and makes mud out of the mass. 
This varnish is probably made from plant resin that 
is carried at the time when they seem to be coming home 
empty handed. This bee, and the two other species of 
mining bee, do more than merely make a hole in the 
. ground and fill one end with food; they actually make 
mud honey-cells which ean be taken from the burrow in- 
*There may be dull seasons, e. g. cold or dry, like sacs when it 
would “eg impossible for a female to make more than on 
