422 bulletin: museum of comparative zoology. 



57. Eciton (Labidus) crassicorne F. Smith. 



Common at Ceara-Mirim and at Carnahubinha (near Natal) where 

 armies were frequently seen toward evening, either on the ground or 

 in the nests of ground-inhabiting ants. 



58. Eciton (Labidus) esenbecki (\Yestwood). 

 A single male of this species was taken at light at Porto Velho. 



59. Eciton (Labidus) sidcatum (Mayr). 

 Several males were taken at light at Independencia. 



60. Eciton {Acamatus) nitcns Mayr. 



A rather large colony of this distinct species, was found emerging 

 at dusk from beneath our house at Independencia. 



61. Eciton {Acamatus) pilosum F. Smith. 



Taken at Independencia and Para. Several armies were encoun- 

 tered. I collected a number of specimens from a large column which 

 was crossing a railroad track at Independencia, whereupon the column 

 broke up, but fgrmed again and continued its march, this time beneath 

 the rail. A column found in the woods at Para was travelling under- 

 ground, except where it crossed a path. Here it emerged and con- 

 structed a trail with embankments on each side. 



62. Ecito7i {Acamatus) Icgionis F. Smith subsp. crenulatum, 



subsp. nov. 



Plate 1, fig. 1. 



Worker. (Plate 1, fig. 1). Length 3.5 to 5 mm. 



Head, excluding mandibles, longer than broad, with nearly straight 

 sides and rounded border; posterior corners angulate. Frontal 

 carinae nearly straight. Outer border of antennal pits strongly 

 carinate. Anterior margin of clypeus flat, projecting at middle. 

 Mandibles stout; the blade edentate. Antennae robust; scape 

 extending a third its length beyond the occipital corners, constricted 



