MANN: THE ANTS OF BRAZIL. 459 
Mamoré Camp 41. The colony was under a log, about three 
inches beneath the surface of the earth. A short perpendicular 
passage led to a single chamber in which was the small fungus garden. 
151. Cyphomyrmex rimosus (Spinola). 
Natal, Baixa Verde, Para, Manaos, Abunda, Porto Velho, and Abunda, 
Bolivia. 
Occurs in small colonies, beneath stones or in rotten wood. The 
death feigning instinct is strongly developed and the insect rolls up 
and remains inert for some time when touched. 
DOLICHODERINAE. 
152. Dolichoderus (Dolichoderus) decollatus (F. Smith). 
This species occurs commonly throughout the greater part of tropi- 
cal South America. A large series of workers, collected at Itacoatiara, 
Porto Velho, and Madeira-Mamoré Camp 39, shows a great deal of 
variation in color. Some have the head and thorax brownish red, in 
others these parts are entirely black. These forms are connected, by 
gradations. 
Most of the workers that I observed were on the trunks of high 
trees. They are slow in motion, and have a habit of remaining motion- 
less for many minutes at a time. When alarmed they drop to the 
ground. 
153. Dolichoderus (Dolichoderus) imbecillus, sp. nov. 
Plate 2, fig. 18. 
Worker. (Plate 2, fig. 18). Length 10 mm. 
Near D. atellaboides. Head, excluding mandibles and the neck, 
longer than broad, with convex sides. Occiput prolonged into a 
neck which in profile is nearly twice as long as thick and moder- 
ately reflexed at the posterior border. Mandibles slender, the blade 
with ten minute teeth and two larger coarser ones apically. Pro- 
notum as broad as long, rounded above and at sides. Mesothorax 
similar to that of D. atellaboides, long and slender; in front with a 
small, rounded, elevated portion, on each side of which is a strong 
impression, extending backward and converging and terminating in 
