MANN: THE ANTS OF BRAZIL. 459 



Mamore 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, Abuna, Porto Velho, and Abuna, 

 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-Mamore 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) imhecillus, sp. nov. 



Plate 2, fig. 18. 



Worker. (Plate 2, fig. 18). Length 10 mm. 



Near D. atellaboidcs. 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 



