60 



PROCEEDINGS OF THE ACADEMY OF 



[1884. 



have a similar habit of thatching their hills, but this is not as 

 decidedl}^ developed and characteristic as with the Rufous ant ; 

 indeed, so far as my observation extends, it is the exception rather 

 than the rule. The thatching habit is possessed by the European 

 representatives of the species (F. rufa), in equal degree with 

 those of our Western plains. 



Interior Architecture. — I requested Dr. De Puy to open the 

 hills by sawing down through the middle to the surface of the 

 ground, and shoveling away one of the halves. This exposed a 

 section view of the interior, and presented the remarkable feature 



shown at fig. 5.^ The 

 central part of the 

 mound, on or about 

 the level of the sur- 

 face, was found to be 

 occupied by a ball of 

 twigs (B, fig. 5), about 

 eight inches in diam- 

 eter ; the sticks are 

 longer and thicker 

 than those used upon 

 the roof, some of them 

 being two aiid a half and three inches long. They were found 

 unmixed with soil or any other substance. Several galleries, 

 about one-fourth of an inch in diameter, led upward from tins 

 billet-globe to the surface, having their outlet by circular open- 

 ings (G) through the thatch. The openings, as seen by Dr. 

 De Puj^, were usuall^'^ near the summit and never more than three 

 in number. In Colorado mounds the openings were spread over 

 the top, and were more numerous. Beneath the faggot-ball a 

 series of galleries, seven in number, extended downward to at 

 least the distance of four and a half feet, the extent of the 

 excavation made by Dr. De Puy. For several inches, immediately 

 below the ball, the galleries were united into a network (n, fig. 



Fig. 3. Flat Circular Mound.— Colorado. 



^ I was unfortunately so situated in the South Park and elsewhere in 

 Colorado, in part by the presence of a sick companion, that I could not delay 

 to open the hills there seen, and make a study of the interior. But I have 

 no doubt that they are arranged like those in Dakota. Will not some 

 observer on that field test the matter by opening a few hills ? 



