Reasoning Powers of Ants 67 
stones; but although great numbers carrying leaves were 
thus cut off from the nest, they would not cross the rails, but 
set to work making fresh tunnels underneath them. Ap- 
parently an order had gone forth, or a general understanding 
been come to, that the rails were not to be crossed. 
These ants do not appear to have many enemies, though I 
sometimes found holes burrowed into their nests, probably 
by the small armadillo. I once saw a minute ‘parasitic fly 
hovering over a column of ants, near a nest, and every now 
and then darting down and attaching an egg to one entering. 
Large, horned beetles (Celosts biloba) and a species of 
Staphylinus are found in the nests, but probably their larvee 
live on the rotten leaves, after the ants have done with them. 
