424 bulletin: museum of comparative zoology. 



dozens, always finding the ant. The colonies contain an enormous 

 number of individuals living throughout the whole plant, all parts of 

 which are hollow. The workers are very aggressive and their sting 

 is quite severe. Whether or not the ants derive any advantage from 

 the tree other than a convenient place to nest I do not know, but 

 there is no doubt that they protect the plant from almost any possible 

 enemy. A Swiss rubber explorer. Otto Schmidt, who has spent many 

 years in the forest and is a keen observer, told me that dead Triplaris 

 plants never contain ant colonies. This suggests that the living 

 plants do offer some attraction to the ant, other than shelter. 



64. Pseudomyrma ocidata F. Smith. 



Many workers and females were found at Natal, nesting in hollow 

 twigs. This is one of the smaller, more delicate species, the workers 

 measuring 4 mm. in length. The head is two and a half times as 

 long as broad, the sides parallel with large, flat eyes. The antennal 

 scapes are short, extending only to anterior third of eyes. The petiole 

 is flattened above, twice as long as broad, in profile nearly twice as 

 long as thick. The color is dark fuscous throughout. 



65. Pseudomyrma caroli Forel. 



Many colonies were found at Itacoatiara, nesting in twigs on small 

 trees near the river. 



66. Pseudomyrma nigriceps F. Smith. 



Several workers were found at Abuna and Madeira-Mam ore Camp 

 41. 



This species resembles P. rufa in structure and size. The color is 

 different and striking, the head being black, and the rest of the body 

 and appendages testaceous. It was not common. 



67. Pseudomyrma fiavidula F. Smith. 



Common at Independencia and Ceara-Mirim, nesting in grass culms, 

 the characteristic nesting site of the species. 



