March, igoi.] SmITH : On SoME DiGGER BeES. 31 



noticed, indicating a depth of from six to twelve inches. From ap- 

 pearance some of these mounds had been there from 2 to 4 days. 

 They were about i^ inches in diameter and half an inch high, with a 

 central opening less than one quarter of an inch in diameter. On the 

 13th over 200 were seen on the same area and on March 15 th the 

 ground was dotted with mounds everywhere in groups of from 5 to 15 

 or more. On this date one of the burrows was followed down to 18 

 inches without finding the end and several of the bees were taken 

 making determination possible. Plaster casting was now begun and 

 the casts obtained ran from 10 to 17 inches in length, a little twisted 

 or bent near the surface, then dropping down almost vertically. 

 Some burrows, however, were absolutely vertical from the top to 

 the bottom. 



March 17th, at a distance of 20 inches from the surface, one cast 

 showed a lateral, set off at an obtuse angle downward from the main 

 gallery. 



March 20th a parchment-like cell was found at the end of a lateral. 

 This cell was about three -fifths of an inch in length, less than one 

 quarter of an inch in diameter, a trifle dilated centrally, though this 

 may have been due to removal from soil, was rounded at the outer or 

 lower closed end and squarely truncate at the upper or open end. In 

 texture it was close and very thin, transparent, not very tough, yet 

 scarcely to be called brittle. It was evidently not intended to be re- 

 sistant, but to keep clean the pasty mass with which it was to be filled. 



March 27th to 31st, bees were engaged in filling these food sacs 

 and on April ist the first completed brood cell with egg in place and 

 finally sealed was found. Of the casts secured up to this time the 

 longest was 27 inches, the range for the beginning of the lateral being 

 from 20 to 27 inches. The laterals themselves varied from 2 to 4 

 inches, an extreme of 6 inches being observed in rare instances. Cells 

 not sealed were filled with plaster when cast, the membraneous cover- 

 ing forming a shining surface at the end. When sealed the closed 

 cell hung loosely to the end of the cast. 



The food stored in the brood cells is a pasty mixture of honey and 

 pollen, but where the insects secured the material at that season was 

 not ascertained. The cell is less than half filled with food and the 

 egg, which is quite large and crescent-shaped, is attached at one side 

 by one end and so curved that the opposite tip rests on the surface of 

 the food mass. The entire insect is less than 1 1 mm. in length, of 



