126 
Psyche 
[December 
denticles near the tip. Posterior surface of labrum with 
ten sensilla. Labium feebly bilobed; anterior surface with 
two or three slight swellings. 
Orectognathus clarki Brown 
(PI. 8, figs. 1 and 2 and 4-10) 
Mature worker larva : Length about 3.8 mm. Shaped 
somewhat like a crookneck squash ; thorax and first abdom- 
inal somite curved ventrally; diameter greatest at abdom- 
inal somite V, decreasing gradually toward the anterior 
end and more rapidly toward the posterior end, which is 
broadly rounded. Anus ventral, with a small posterior lip. 
Leg and wing vestiges distinct. Spiracles small. Integument 
of the ventral surface of the thorax and abdominal somites 
I and II and of the dorsal surface of a few posterior somites 
with a few transverse rows of minute spinules. Body hairs 
moderately numerous. Of three types: (1) short to mod- 
erately long (0.07-0.14 mm), bifid, with the branches short 
to long, equal, denticulate and recurved at the tip, on the 
lateral and dorsal surfaces, the most abundant type; (2) 
on the ventral surface, short to moderately long (0.07- 
0.175 mm), slightly curved, distal half denticulate, usually 
with a minute hook at the tip; (3) a few (about eight) 
on the dorsal and lateral surfaces of each somite, long 
(0.175-0.245 mm), sparsely denticulate, with a minute hook 
at the tip and a short denticulate lateral branch near the 
base. Cranium vaguely subhexagonal in anterior view, 
scarcely broader than long. Antennae with two or three 
sensilla, each bearing a spinule. Head hairs few, short to 
long (0.035-0.175 mm), flexible, with a few denticles near 
the tip. Labrum small; subrectangular, width twice the 
length ; with a median impression of the ventral border 
which extends as a trough onto the anterior surface; an- 
terior surface of each half with four minute hairs and/or 
sensilla ; lateral borders with a few isolated spinules ; ven- 
tral border with minute spinules and two contiguous sen- 
silla; posterior surface smooth near the ventral bordm% 
elsewhere spinulose, the spinules minute and in short trans- 
verse rows medially, but isolated laterally; posterior surface 
with about 10 sensilla. Mandibles heavily sclerotized. 
