1957] Brown — Orectognathus and Amoldidris 27 
The discovery of phyllobates on foliage well above the 
ground, and Wilson’s observations on O. sarasini climbing 
treetrunks at night, tend to show that Orectognathus may 
be more or less generally a nocturnal, arboreal or subar- 
boreal forager. That 0. clarki Brown may have similar 
habits seems likely, in view of the fact that this species 
is never seen foraging outside the nest during the daytime 
(so far as limited observations go). 
Key to Orectognathus species, based on workers 
1. Each occipital lobe drawn out as a stout, acute, dorsally 
curving tooth (n. Queensland) satan Brown 
Occipital lobes bluntly rounded posteriorly, without 
teeth 2. 
2. Propodeal spines about 3 times as long as the distance 
between the centers of their bases; body and limbs 
with abundant, generally-distributed, fine, short, erect 
pilosity; petiolar node very slender, unarmed. (Queens- 
land) sexspinosus Forel 
Propodeal spines markedly less than 3 times as long 
as the distance between the centers of their bases; 
either the body without generally-distributed pilosity, 
or else the petiolar node bidentate, or both 3. 
3. Inner mandibular border just basad of apical teeth 
with a small tooth or dentiform angle, acute to sub- 
acute at tip 4. 
Inner mandibular border without an acute or subacute 
tooth or toothlike angle in the region just basad of 
the apical teeth, though some species have a rounded 
flange or thickening in this region 5. 
4. Paired anteocular teeth, and a pair each on the vertex 
and petiolar summit, developed and acute ; erect pilosity 
present and generally distributed over body (New 
Guinea) csikii Szabo 
Anteocular teeth and teeth of vertex obsolete, petiolar 
teeth nearly so ; erect hairs confined to mandibles, 
under-mouthparts and gastric apex (Lord Howe I.) 
hoivensis Wheeler 
5. Anteocular teeth lacking or represented only by an 
obtuse angle on each frontal carina; head narrower, 
Cl normally 75-80 in the worker 6. 
