A CRUSTACEAN- EATING ANT. 257 



could not, therefore, observe whether the work of the colony is 

 carried on by slaves. What firmly convinced me, nevertheless, 

 that this species is a slave-holding ant, was the following : The 

 mandibles are long and sickle-shaped, almost as much so as in 

 our German slave-holders, and little adapted for working, as 

 they have no masticatory border. They could of course, be of 

 use in killing termites, as Forel supposes to be the case in this 

 genus, but the place were I found the species under consider- 

 ation was far removed from all termite nests. It was on the 

 sea-shore between blocks of coral, where I saw about fifty indi- 

 viduals in a troop, as it were, on the march. It was evident 

 that the troop had left the nest for the purpose of perpetrating a 

 robbery in common. That this robbery, after what has been 

 said, was for the purpose of obtaining slaves, seems probable." 

 I venture to maintain that Dahl is mistaken in supposing that L. 

 bisuiarckcnsis is a dulotic ant, as a perusal of the above quoted 

 passages from Wroughton's work will suffice to show. 



It is also evident from the observations of Wroughton and 

 Aitken that the Indian species of Lcptogcnys differ widely in habit 

 from L. elongata. The colonies of the latter species are very 

 small, rarely containing more than a hundred individuals, whereas 

 the colonies of the Indian species appear to contain thousands of 

 workers. Moreover, the workers of L. elongata leave the nest 

 singly and hunt about timidly for their phlegmatic and defenceless 

 prey, whereas the Indian species hunt in well organized files 

 somewhat after the manner of the driver ants and ants of visita- 

 tion (Dorvlns and Ecitoii). And such diversity of instinct is 

 exhibited not only in the same genus but within the confines of 

 the same subgenus (Lobopelta). 



In conclusion I give the synonymy and a description of all 

 three phases of the North American Lcptogenys. 



LEPTOGEXYS (LOBOPELTA) ELONGATA (Buckley) Wheeler. 

 Ponera elongata Buckley, Proc. Ent. Soc. Phila., Vol. VI., 1866-67, 

 p. 172, . 



? Ponera Icxana Buckley, ibid., p. 170, . 



Lobopclta septentrionalis Mayr., Verhandl. k. k. zool. bot. Hes. Wien, 



Bel 36, 1886, pp. 438, 439- 



Leptogenvs septcntrinnalis Emery, Zool. Jahrb. Abth. f. Syst., Bel. 8, 



1894, p. 268, '4 . 



