1907.] Wheeler, Fungus-growing Ants of North America. 693 



daily of Icevigata, are less populous than those of sexdens. The nests of 

 cephalotes occur from sea-level to an altitude of more than 1,000 m., those 

 of sexdens only in the low-lying regions. 



According to von Ihering (1898) the nest of the Brazilian Aita sexdens 

 differs from that of the Colombian form described by Forel. It consists of 

 from one to two dozen chambers, each 25-30 cm. in diameter and 12 to 

 15 cm. high, with a flat floor and arched ceiling. Each of these chambers, 

 panellas (pots) or pratos (plates) as they are called by the Brazilians, has 

 one or more, rarely two, galleries entering it at the side and connecting it 

 with the other cavities and the vertical shafts leading to the surface of the 

 nest. The chambers are | to 1 m. apart and are excavated at a depth of 

 4 to 6 m. below the surface or even lower. The fungus gardens are built 

 up on the flat floors of the chambers. Von Ihering found that when the 

 nests are inundated the ants at once remove portions of their fungus gardens 

 to higher ground. When this is impracticable or the inundation is very 

 great, the population of the nest forms a ball held together by the closed 

 jaws of the workers and enclosing in its interior a portion of the fungus 

 garden and probably also the queen. This ball then floats on the water 

 till carried ashore, when the ants land and start a new nest out of reach of 

 the flood. Von Ihering says that his neighbor took advantage of this habit, 

 which by the way is also exhibited by several other tropical ants (Anomma, 

 Solenopsis geminata, etc.), to free his premises from the leaf-cutting Attoe, 

 by rowing about in his canoe, catching up the floating balls and throwing 

 them into a bucket of boiling water. Von Ihering also gives an interesting 

 account of the it^as, or virgin queens of Atta sexdens. At the time of swarm- 

 ing these are captured in great numbers by the Brazilians. The i9a hunter 

 stations himself at the entrance of the nest with his feet in a tub of water in 

 order to protect himself from the savage soldiers and workers, and collects 

 the females while they are issuing from the galleries. A successful catch 

 may yield as many as 12 to 20 litres. The gasters of these i^as, removed 

 from the thoraces, legs and heads and roasted with salt, garlic and mandioca 

 meal are eaten as a delicacy {" pa.ssoca") in many parts of Brazil. 



Forel (1899-1900a, 1901) has also recorded a few notes on the fungus- 

 gardens of a colony of Trachymyrmex septentrionalis which he observed at 

 Black Mountain, Xorth Carolina, but he adds little to the above cited 

 descriptions of ^Morris, INIcCook and Swingle. Forel (1905) later pub- 

 lished some notes of Goeldi on the nests of Acromyrmex octospinnsiis, the 

 fungus gardens of which are built over the stems of plants and fully exposed 

 to the air in the damp forests of Para. Two photographs accompanying 

 the article show that this fungus garden consists of a niunber of separate 

 portions unlike the single garden which Urich and Forel describe this ant 

 as making when nesting in the ground. 



