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Psyche 
[Vol. 92 
in the myrmicine harvesters Pogonomyrmex barbatus, P. maricopa 
(Holldobler 1976), and P. mayri (Kugler, 1984); another myrmicine 
harvester, Pheidole militicida (Holldobler 1976; Holldobler and 
Moglich 1980), and various formicines such as Formica species 
(Rosengren, 1971: 7-57), show route fidelity: tendency of workers to 
exit along the same trunk route in successive trips. It is possible that 
foragers of these species and of R. sp. 12 not only forage in the same 
direction in successive trips, but also visit the same areas in the 
foraging grounds, as has been demonstrated for foragers and aphid- 
tenders of the formicines Cataglyphis bicolor (Harkness and Hark- 
ness 1976), Formica obscuripes (Herbers 1977), Formica yessensis 
(Higashi 1978), F. subnuda, F. subsericea and Camponotus nove- 
boracensis (Ebbers and Barrows 1980): the phenomenon of ort- 
streue (Oster and Wilson 1978: 152). 
Among ponerines, carrying has also been implicated in nest- 
moving in Diacamma rugosum (Fukumoto and Abe, 1983), 
Bothroponera tesserinoda (Maschwitz et al., 1974; Moglich and 
Holldobler, 1974), and Ophthalmopone berthoudi (Peeters, 1984). 
However, D. rugosom also employs tandem running and in B. tesse- 
rinoda tandem running is the chief method used. 
The extensive “carrying” between nests indicates that, although 
considerable hostility can be demonstrated both between foraging 
workers and by our “hostility tests”, such internest hostility is not 
invariable. We are uncertain at present whether certain groups of 
nests are linked as multinest colonies, or whether the situation might 
not be more complex. It is possible, for example, that the funda- 
mental selection unit above that of the individual in populations 
such as that of the observed R. sp. 12 and of some Formica species 
(Scherba 1964) is not the nest but the matriline or sibship. Nests 
would contain cooperating matrilines, and carrying may represent 
attempts to maintain nests at adequate strength via the antnapping 
of outsiders. The rather confused nature of carrying, with workers 
making trips in several different directions, is consistent with the 
matriline-selection hypothesis, but is also observed in some other 
ants during nest-moving when scouts “choose” different destinations 
(Moglich and Holldobler 1975; Rosengren and Pamilo 1983), and 
such multi-directional carrying can be likened to a voting system for 
choosing the best nest-site (Rosengren, 1971: 21; Wilson, 1971: 224). 
The observation of ants marked in the 57-59-60 system in nest 61 in 
