Figure 6a.

Casts of Pogonomyrmex badius nests of increasing size: (A) a very small nest with a single vertical chamber series and shaft; (B) a medium-small nest with the beginning of a second vertical series and shaft; (C) a large-mature nest with 4 vertical series and shafts. The right nest (C) cast is of dental plaster, the middle (B) of aluminum, and the left (A) of zinc. The middle cast is incomplete, the lowest chambers having failed to fill with metal. Its maximum depth was probably intermediate between the large and small casts (photos by Charles Badland). (continued on page 8)