130 
Psyche 
[December 
Genus Mesostruma Brown 
Shaped somewhat like a crookneck squash; thorax and 
first abdominal somite forming a long slender neck, which 
is strongly curved ventrally; metathorax constricted; re- 
mainder of abdomen subovoidal. Body hairs sparse. Anten- 
nae small ; with three sensilla each. Head hairs minute 
and simple. Posterior surface of labrum with ten sensilla. 
Mesostruma laevigata Brown 
(PI. 9, figs. 1-3) 
Length about 4 mm. Shaped somewhat like a crookneck 
squash; thorax and first abdominal somite forming a long 
slender neck, which is strongly curved ventrally; metatho- 
rax constricted ; remainder of abdomen very stout and sub- 
ovoidal. Anus ventral. Spiracles small; the mesothoracic 
the largest, the diameter decreasing posteriorly. Inte- 
gument thin, flimsy and apparently without spinules. Body 
hairs apparently sparse. Cranium vaguely subhexagonal 
in anterior view; slightly broader than long, broadest at 
the antennal level; occipital border feebly concave. Anten- 
nae very small, each with three sensilla, each of which 
bears a spinule. Head hairs few, simple, minute (about 
0.012 mm long). Labrum small; twice as broad as long; 
subrectangular, with the ventral corners rounded and the 
medial border slightly concave; anterior surface of each 
half with three or four sensilla near the ventral border; 
ventral border with two clusters of two or three sensilla 
each ; posterior surface of each half with three isolated and 
two contiguous sensilla; dorsal 2/3 of posterior surface 
spinulose, the spinules minute and in short arcuate rows. 
Mandibles with the apical half heavily sclerotized, sub- 
triangular in anterior view; apical tooth rather long and 
tapering to a rounded point, a narrow blade extends medial- 
ly off the anterior surface and bears two round-pointed 
teeth. Maxillae short and lobose ; palp chair-shaped with one 
lateral (with a spinule) and four apical (two encapsulated 
and two bearing a spinule each) sensilla; galea a frustum 
with two apical sensilla. Labium with numerous short rows 
of minute spinules on the anterior surface; palp similar 
to maxillary palp but shorter ; an isolated sensillum between 
