78 
Psyche 
[March 
Sculpture shining, with foveae much as in the worker, but also 
with rugulae and more opaque around the eyes, posterior scutellum, 
dorsum and sides of propodeum, metanotum and sides of petiole. 
Pilosity fine, rather short, moderately abundant, decumbent to sub- 
erect, generally distributed over body, scapes and legs. Color light 
yellowish-brown, gaster more brownish; vertex infuscated near ocelli 
and in back of compound eyes. 
Holotype (from unnumbered colony, i April 1969) and paratypes 
(colonies ICA-69, 30 March 1969; M-252 and an unnumbered 
colony, plus strays, 1 April 1969) taken from Le Pouce (mountain), 
Mauritius, in native forest between 700 and 800 meters elevation on 
the plateau just below the peak (W. L. Brown, Jr.). Holotype and 
paratypes deposited in Museum of Comparative Zoology, Harvard 
University, Cambridge, Massachusetts, U.S.A. Paratypes in Cornell 
University Collection, British Museum (Natural History), Aus- 
tralian National Insect Collection, Canberra, Australia, and else- 
where. 
P. avium belongs to the stictum group of Proceratium , containing 
two other species. P. stictum (Brown, 1958 ,*366) has been known 
only from a single worker from North Queensland. (Now I have 
seen males apparently belonging to stictum , taken at light by E. S. 
Ross and D. Q. Cavagnaro at Brookvale, Queensland; and R. W. 
Taylor showed me a series that I was only able to examine hurriedly, 
but which looked to me like stictum , from his collections made in 
North Borneo.) The second species of the stictum group is P. goliath 
(Kempf and Brown, 1968:94 ff.) from Costa Rica. P. aviu?n is 
distinct from both of these species in its much shinier and coarser 
sculpture and in details of the shape of the trunk, particularly its 
completely unarmed propodeum, in its longer antennae, and in its 
less strongly undercurved gaster. P. avium is also much larger than 
P. stictum , but smaller than P. goliath , and its eyes are relatively 
larger than in either of these species. In fact, P. avium might well 
go into a group of its own, but the structure of the clypeus, mandi- 
bles, and petiole are so much like those of P. stictum and P. goliath 
that the relationship of these three species is obvious. 
The characters they share are also primitive for the genus Pro- 
ceratium , and this with the widely discontinuous known distribution 
of the group suggests that the stictum group represents the relicts of 
an early dispersal wave of a primitive Proceratium stock that spread 
widely over the earth and was overtaken (except on Mauritius) by 
later waves of more advanced Proceratium groups. Possibly wide- 
