1925] Guests of Eciton hamatum Collected by Prof. Wheeler 175 
the posterior third of sides; anterior border concave, posterior 
border convex; anterior three-fourths of sides elevated into an 
immense, rounded margin, with concave outer and copvex inner 
sides, projecting forward and slightly outward as somewhat 
flattened lobes, the outer corners of which are obtusely angulate, 
the inner corners broadly rounded, terminating behind as thick 
gibbosities; in profile the dorsal portion of the margin is evenly 
and shallowly concave; surface rugosely punctate, the disc also 
with elevated reticulate lines. Elytra densely punctate, more 
finely than pronotum, not striate; surface at anterior margin 
with a series of six large, rounded, rather shallow foveae; anterior 
two-thirds of sides elevated into a pair of huge marginal masses, 
subequal in length, the anterior (humeral) one higher and broader 
than the other, constricted laterally at base, broad above, strongly 
and broadly impressed longitudinally at middle and very roundly 
margined at sides; posterior lobe separated from the humeral 
by a lateral construction and a narrow transverse impression, 
broadly concave above, with the margins narrowly rounded, 
evenly sloping behind to the sides of disc and terminating at two 
thirds the distance to posterior border of elytra. 
Propygidium and pygidium punctate throughout similar to 
the elytra. Prosternal keel narrow, strongly excised behind, 
surface nearly flat, sides between coxae feebly concave, weakly 
margined, the marginal lines divergent in front, terminating 
before the middle; surface of lobe rugosely punctate, of keel 
more finely punctate, with a few foveae on posterior portion. 
Mesosternum at sides with sharp elevated margins and at 
middle with a more elevated longitudinal carina, thickened 
posteriorly, bordered in front, the surfaces between this and the 
marginal carinae strongly concave. Metasternum gibbous at 
middle near base, impressed in front of this, with an indistinct 
median longitudinal line. 
Legs long, slender, outer borders of tibiae narrowly cultrate, 
anterior and middle pair sinuate at outer border, posterior tibiae 
feebly and roundly angulate well posterior to middle. 
Type locality . — Barro Colorado Island, Panama. Aug. 1, 
1925 (Wheeler). 
