stridulation wn ants. 209 
Worker minor. — Amazon Valley. Similar to the 
major, with the exception that the sculpture is much 
finer, and the lines of the stridulating band less elevated. 
Winged female. — Demerara. (Dissected specimen). 
The neck of the segment is very short—indeed, it scarcely 
exists except in the dorsal region; in this latter part 
the sculpture on it is very fine and dense, and on the 
middle there is a band of stridulating lines, which are 
finer than in the worker. The scraping band on the 
hind margin of the second node is very prominent all 
across the dorsum of the segment. The size of this 
individual is enormous in comparison with the workers, 
and yet the stridulating lines are finer. 
Male.—Demerara. (Dissected specimen). The neck 
of the segment is almost absent, even the dorsal region 
scarcely prolonged enough to form a scutellum. The 
sculpture on the surface of the dorsal region is very fine 
and densely sculptured, and on the middle forms densely 
placed and regular fine lines of considerable length in 
the transverse direction ; the surface on which the lines 
are placed is slightly convex in the transverse direction. 
The second segment of the node is provided behind 
with a ridge, that is comparatively little prominent at 
the sides, but is very much so in the middle, and is 
curvate so as to correspond with the slight convexity 
of the surface on which the stridulating lines are placed. 
Atta, sp.?.—Guatemala. I have experimented with a 
number of specimens in spirit entrusted to me by Mr. O. 
Salvin, and I find that the various forms of workers 
produce quite audible sounds ; there are, however, some 
individuals which I have failed with; my repeated efforts 
to produce sound by causing the parts to execute the 
appropriate movements having been quite unsuccessful. 
A female stridulates more loudly than any ant I have 
examined. Fig. 7. 
In the case of this interesting genus of ants—the leaf- 
cutting ants of books of travel—I have found more 
audible sounds produced than in any other ant. The 
function of the worker majors of these creatures has 
been a mystery, Bates having quite failed to detect any 
use for them. The fact that they are endowed with 
sound-producing organs renders it possible that they 
may be individuals whose deficiencies in other respects 
may make them more sensitive in the matter of sounds. 
