BRACHYGLUTINI 197 



medianly, (4) first visible stemite evenly convex, not flattened, (5) anterior 

 and intermediate trochanters simple, (6) tibiae simple. 



Described on eight specimens, all collected on Barro Colorado Island, Gatun 

 Lake, Panama Canal Zone. Female paratype collected at light at night on 

 August 2, 1935, by Alfred Emerson; holotype male, allotype female and two 

 paratype females (July 7, 1936), paratype female (July 15, 1936), paratype 

 female (July 17, 1936) collected at night at light by the author; paratype male 

 collected July 29, 1936, at night from overnight nest of Eciton burchelli Westw. 

 by the author. 



With reference to this last paratype, the host ants were very kindly iden- 

 tified by Dr. Neal Weber. Regarding the host, I quote from my field notes: 

 Wednesday, July 29, 1936 



"At about Snyder-Molino trail 4, Dr. Chickering and I saw a column of army 

 ants moving along a log late in afternoon — the column was about ten ants 

 wide. We followed column to large tree on trail fifty feet away and there, be- 

 tween two plank-buttresses the ants were forming nest of their own bodies, 

 hanging in festoons 6 to 12 inches long, and the trunk and ground covered 

 with them. We estimated that the nest was eight square feet and two inches 

 deep (2305 cubic inches). Allowing 173 ants to a cubic inch and a conservative 

 army ant volume of 90 cubic millimeters each, the population worked out at 



about 388,000 army ants. Collected quart of ants returned at 9:30 P.M. 



to find ants on the march, with pupae and larvae, the soldiers guarding column 



of ten ants wide as before. Nest about gone Thursday, July 30, 1936. By 



9:30 A.M. ants had entirely disappeared." 



The rapacious habits of these ants are well known and their autecology 

 has been reported recently (Schneirla, 1940) from this island. With this par- 

 ticular colony of Eciton burchelli Westw. there also occurred the limuloids 

 Cephaloplectus mus Mann and Limulodes brachyscelis Seevers and Dybas. 



With respect to Decarthron euspinifrons, I am inclined to place this 

 pselaphid as a synoekete of burchelli, as the male collected was in the midst 

 of a long festoon of ants and certainly would be quickly destroyed unless it was 

 a tolerated guest. Since other specimens were collected at light at night, the 

 pselaphid is probably a facultative synoekete enjoying its nocturnal pselaphoid 

 heritage. 



Euspinifrons is structurally very isolated in the genus, having its nearest 

 relative in monoceros (Schaufuss) of Dutch Guiana, and its zoogeographic 

 affinities seem to be South American rather than Central American. 



Two species are worthy of additional note. 



Bryaxis denticornis Schaufuss (1880, p. 15) of Yucatan, Mexico, was placed 

 by Sharp (1887, p. 24) as Decarthron denticorne (Schaufuss), and in this allo- 

 cation was doubtful, since Schaufuss did not describe the thorax of the species. 

 Not listed by Raffray (1904, 1908) in genus. 



Batrisus monoceros Sharp (1887, p. 14), based on one male from 7000 to 

 9000 feet in the Quiche Mountains of Guatemala, but not figured, is not listed 

 by Raffray (1904, 1908) in Batrisini. I am struck with the similarity of Sharp's 



