234 KANSAS UNIVERSITY SCIENCE BULLETIN. 



and then sealed the entrance to the burrow, always leaving a 

 long vacant space in the burrow above the upper cell. The 

 thickness of this mud plug which she puts in the entrance of 

 the burrow I have found to vary from one-eighth to seven- 

 sixteenths of an inch. The plug with which the cells were 

 closed varied in thickness from one-eighth to five-sixteenths- 

 of an inch. 



The locality of the nest, after it was closed, was often be- 

 trayed by a small basin-like depression, of which the closed 

 entrance to the burrow was the center. The depression varies 

 from one-half to three-fourths of an inch in diameter. It was 

 caused by the removal of earth from the edges of the burrow 

 entrance, to be used in sealing the burrow. 



The nests whose entrances opened in the face of the earthen 

 bank were similar to those already described, in that the cells 

 were arranged one above the other as a series of enlargements 

 of the burrow at its lower end. The cells were nearly all 

 vertical, as was most of the burrow above the cells, although it 

 entered the bank horizontally. 



The number of cells to each nest was a marked difference 

 between the nests of this colony and those previously de- 

 scribed. The eight nests had a total of thirty-seven cells ; the 

 smallest number of cells in one nest was three; the largest 

 number, seven. With one exception, the cells were arranged in 

 a single gallery. The cells of the one nest which did not con- 

 form were in two galleries of four and three cells each, one 

 excavated directly behind the other. 



The cells in this colony were quite nearly alike in shape and 

 size. All resembled barrels with rounded ends. The average 

 height was fifteen-sixteenths of an inch ; the average diameter 

 one-half inch. The burrow before it reached the cells was 

 from one to three inches long. Its diameter averaged nine- 

 thirty-seconds of an inch. The depth depended upon the num- 

 ber of cells in the nest. In one in which there were six cells 

 the base was eight inches below the entrance. The entrances 

 to the burrows and the cells were sealed with mud plugs vary- 

 ing from one-eighth to one-fourth inch in thickness. 



Let us now observe the building of a nest. A female dorsalis, 

 running nervously over an open space about the size of my 

 hand, in an Osborne county bottom-land pasture, attracted my 

 attention. She would stop for an instant, and with her fore 

 feet would sweep dust rapidly under her body. Then she 



