364 Trans. Acad, Sci. of St. Louis 
a waxy substance for both partitions and plugs. The 
cocoons which were found in this cavity in the timber 
were in mud cells just large enough to hold them, and 
showed every evidence of having been made by this 
species. This portion of the tunnel must have been used 
for more than one generation of bees, for at the far 
end some debris, including old cocoons, had been swept 
back. The portion of this tunnel indicated by 9 in the 
figure contained an old Lepidopterous cocoon and bits 
of the old pupal case. The caterpillar had evidently 
sought shelter in the hole in the board, and pupated 
there. The tunnel at 2 had a mud partition about 2 inches 
from the turn in the gallery; this marked off one cell 1 
inch long which was empty, although it may have con- 
tained a larva that fell out when the board was broken 
and pulled out of the cabin doorway. 
I have mentioned in a previous publication that it 
seems that Monobia does not spin cocoons. In this 
nest too I found unclad larve (fig. 42) but I also no- 
ticed that certain portions of the wall were veneered 
with a substance that had hardened into papery material, 
white and very thin. This may have been substance 
from the intestinal tract eliminated just before pupation, 
for it was not distributed with any degree of regularity. 
In one cell the entire mass was spread on the partition, 
with the overflow covering a portion of the floor. 
The portion of the tunnel indicated by 5, and its op- 
posite wall by 6, had been burrowed by the carpenter- 
bee and showed unmistakable signs (the remains of mud 
partitions) of having been used later by the Monobia 
mud wasp. This gallery was clean and empty except 
that at its extreme end was a cocoon of a cuckoo-bee. 
The last wasp to fall heir to this much-used nest had 
been Chlorion auripes, for the entire gallery from 1 to 
