Transactions Texas Academy of Science. 
63 
saliva to this last work thereby manufacturing a kind of varnish 
with which to increase the durability of the structure. At any 
rate the interior presents a smooth surface while the exterior is very 
rough, each elevation representing the amount of mud brought in 
by a single load. 
At 5 :15 the cell was ready to receive the spider with which it was 
to be stored. Mellipes , however, does not have good luck in find- 
ing the spiders she wants. On this occasion it took her twenty- 
four hours to store the cell, on another forty-six hours elapsed be- 
tween the completion and the storing. At 6 :30 p. m., August 1, 
the wasp was just putting the finishing touches on the disc-shaped 
lid with which she closed the cell. I failed to catch the wasp at 
this time though I succeeded ten days later while she was at work 
under another leaf in the same angle of the elm tree roots. 
The wasp had built three barrel-shaped cells tapering slightly at 
both ends, each cell about eight mm. long and four in greatest 
diameter. One cell was independent of the other two which were 
built together at an angle of about 120 degrees. The angle seems 
to depend on the conditions under which the cells are built, for 1 
once found in a narrow crease of a wagon cloth five cells of mellipes 
attached one to the other in a straight line. Having reached home 
with my trophy I could not resist opening at least the cell last 
made to ascertain the condition of the spider and the position of 
the egg. Both are well shown in Fig. 20. The spider, it will be 
seen, had lost all its legs but the front pair and the egg was placed 
across the ventral surface of its abdomen. The spider was stuffed 
into the cell head first. 
But egg and spider were not the only occupants of the cell. To 
my great astonishment I became aware of a tiny parasitic wasp,, 
no larger than Ageniafs egg itself, resting on the egg. The para- 
site ( Ophelinus florifrons , Ashm.) had been imprisoned and when 
I found it, was evidently about to infect the egg of its host. It 
had not yet laid its own eggs into that of melipes, however, for the 
latter developed normally. It hatched and the larva in due time 
devoured every trace of the spider. August 8 it spun a fine white 
cocoon, which, it might be added, never changed its color. This is 
also true of the cocoons of A. subcorticalis. The larva succeeded in 
spinning its cocoon with support only from the low sides of the 
broken cell. It is also significant that the larva and pupa both 
developed quite as well in the light and without the protection of 
the mud cell, also in the dry atmosphere of the laboratory, as they 
would have done in their natural haunt on the banks of Waller 
