114 Psyche [March-June 
ration. The same is true of the pedunculate petiole, for the new 
species described in this paper has a petiole that is closely 
similar to that of several species in the subgenus Orthocrema. 
The one remaining separatory character is the structure of the 
epinotal spines and, since spine length is such a notoriously 
variable characteristic, one hesitates to place much value on 
such a character. In Rhachiocrema, however, the spines show 
certain features that appear to exclude the possibility of con- 
fusion with long-spined species in other subgenera. In addition 
to their extreme length the spines of Rhachiocrema are not 
evenly tapered from base to tip. The taper of the thickened 
basal half of each spine differs from that of the thinner apical 
half. This break occurs suddenly at a point near the middle of 
the spine so that when the spine is viewed from the correct 
angle the two parts can be clearly distinguished. In other spe- 
cies of Crematogaster having long epinotal spines, as for exam- 
ple in the South American species acuta , the spines are evenly 
tapered from base to tip. 
Key to the species of Rhachiocrema 
1. Anterior peduncle of the petiole fully as long as the node itself, the node 
rounded above and without posterior angles; epinotal spines reflexed at the 
tip (New Guinea) paradoxa 
Anterior peduncle of the petiole shorter than the node, the node flat above 
and with distinct posterior angles; epinotal spines straight at the tip 2 
2. Entire insect shining and finely punctate; clypeus with five or six longitudinal 
ridges; color black (British Solomons) wheeleri 
Head shining with sparse punctures, sides of the mesonotum and much of the 
epinotum densely and coarsely punctate and subopaque; clypeus bicarinate; 
color sordid yellow, the gaster castaneous, (Borneo) macracantha 
Crematogaster ( Rhachiocrema ) macracantha sp. nov. 
Worker: Length 3.5 mm. 
Length of the head from the anterior edge of the clypeus to 
the occipital border 0.75 mm. The head is slightly longer than 
broad with the occipital angles broadly rounded and the middle 
of the occiput flat. The sides in front of the eyes are almost 
straight, converging gradually to the level of the antennal inser- 
tions but more sharply convergent and more curved from that 
point to the insertion of the mandibles. Eyes suboval, the lower 
edge much more flattened than the upper, moderately convex 
with about 10-11 facets in greatest diameter, the facets coarse. 
Clypeus moderately projecting with two prominent carinse. 
