.l.\'T-.\ESTS. 199 



E. Accessory Structures. 



a. Succursal nests. 



b. Covered runways. 



c. Tents, or pavilions. 



Accurate delimitation of the foregoing categories is, of course, 

 impossible, since two or more of them may be combined in the same 

 nest. Thus some ants construct carton nests in dead logs or under 

 stones, others extend their galleries from dead logs into the underlying 

 soil. Then there are also transitional forms between the various cate- 

 gories, as, for example, between the small and 'large crater nests, and 

 between the latter and mound nests. And lastly, a single formicary 

 may gradually pass through a series of these categories during its 

 growth and development. 



Nests in the Soil. These always consist of a subterranean portion 

 comprising a number of more or less irregular excavations and may or 

 may not have a definite superstructure surmounting the entrance or 

 entrances (Fig. 106). The excavations, which are usually widely sepa- 

 rated but are occasionally compactly branching or anastomosing, may be 

 divided into chambers and galleries. The former are more spacious, with 

 flattened floors and vaulted roofs, but of extremely variable size and 

 outline ; the latter are more tenuous, being more or less tubular con- 

 nections between the chambers themselves and between these and the 

 nest openings. Chambers and galleries are most sharply differentiated 

 from each other in the fungus-growing ants, especially in the typical 

 genus Atta. These nests will be described in greater detail in a future 

 chapter. Suffice it to say in this place that the chambers of ants of the 

 subgenera Trachymyrmex and Mycetosoritis are large spherical cavi- 

 ties, whereas the galleries are uniform, tubular passages entering and 

 leaving the chambers at rather definite points. In several species the 

 chambers have the appearance of being strung along a single vertical 

 gallery like beads on a thread. The chambers in most ant-nests are 

 used as nurseries for the brood and for the assemblage of the ants 

 themselves. In species which store seeds several of the chambers near 

 the surface may be set apart as granaries, and in the Attii nearly all the 

 chambers of the nest are given up to fungus gardens. In the nests of 

 the honey-ants the replete workers, or honey-bearers, hang from the 

 hard, vaulted roofs of the chambers furthest removed from the surface, 

 while the brood is reared in the. small and more superficial apartments. 



The incipient nests of all soil-inhabiting species are essentially alike 

 in presenting only the subterranean excavations. Ants in this stage of 

 colonial development are exceedingly timid and take the greatest care 



