1974] 
Brown — Ant Genus Proceratium 
8l 
Among the ants of the present endemic fauna, it is difficult to pick 
out any that might be serious competitors of Proceratium avium. 
Our assumption here, of course, is that P. avium subsists primarily 
on arthropod eggs, probably mainly the eggs of spiders. (But the 
assumption rests on only a few observations, which need augmenta- 
tion.). Perhaps Solenopsis mameti , a much smaller ant that nests 
mainly in rotten wood in forest shade, would qualify as a competitor. 
This judgement is based on the generalized feeding habits of similar- 
sized Solenopsis elsewhere in the world, and we have absolutely no 
direct information on the food of S. mameti. At least, the species 
has not been seen foraging on open paths or tree trunks during 
the day. 
The bright red color and open-trail foraging of P. avium suggests 
reduced predation pressure in the Mauritian native forest habitat, 
but the possible mimicry with Pristomyrmex bispiwosus could on the 
other hand indicate that predator pressure is appreciable, and in some 
way answered by protective properties. 
In summary, a reasonable hyothesis to explain the atypical “epi- 
gaeic characters” of P. avium assumes that the ancestral stock reached 
Mauritius a long time ago from Africa or Asia in a floating log or 
rotting branch, and established itself in an ant-poor environment that 
was perhaps also weak in the kinds of predators that attack open- 
foraging ants. Evolution in such an environment, it is argued, led to 
the reacquisition of characters that had been lost by the parent Pro- 
ceratium stock during continental specialization to cryptic environ- 
ments in which arthropod (spider?) eggs had become its main food. 
Another hypothesis is that the Mauritian Proceratium retains a 
sculptural-pilosity pattern primitive for the genus, and that its arthro- 
pod egg-feeding proclivities were acquired in an open-foraging situa- 
tion that elsewhere has since been modified under continental pressures 
of competition and predation. 
In order to throw light on the question, it would be interesting to 
know exactly what animals the prey eggs on Mauritius belong to, and 
where and how they are taken by the ants. It may be that we shall 
never find out, for the mountain forests of Mauritius appear to be 
teetering on the brink of extinction. 
Notes on other species of Proceratium 
Since my summary of Proceratium (Brown, 1958: 241-248), the 
genus has been found in additional parts of the world. Leston 
