OF WASHINGTON. 77 
says, one can examine many males, and in all the abdomen appears to be 
excavated, the, excavation extending in an elongate-triangular shape from 
the apex of the fourth segment to the tip of the abdomen. Such will be 
found to be the case in most specimens which have been collected in 
alcohol, but in well-preserved specimens there should be no doubt about 
the real nature of this structure, which can be described briefly as follows : 
Two more 'or less slender, movable appendages arise from the apex of the 
fourth ventral segment; the abdomen is not excavated, but the last segment 
is emarginate, or notched. The appendages are stiff, of nearly equal width 
throughout, covered with rather sparse, black hair, and movable in an up- 
and downward direction, but do notseem to be capable of lateral movement. 
When closely applied to the surface of the abdomen they resemble in an 
extraordinary degree the abrupt ridges which in the males of certain other 
Coleoptera limit the excavation of the abdomen. In three species (m. 
nigra, atra zndjlavtpennis) the appendages are straight or nearly so, and 
start from one and the same point at the apex of the fourth segment, diverg- 
ing posteriorly; while in M. rufa the appendages are curved and widely 
distant at their starting place. Of the remaining species no males could 
be examined. 
Mr. Schwarz then read the following note : 
STRIDULATION IN HARPALUS CALIGINOSUS. I inquired of Dr. Horn, 
while he was in Washington on a recent visit, concerning his observation 
(alluded to on p. 51), and he told me that there can be no doubt regarding 
the stridulating power of Harpalus caliginosus. One evening his attention 
was called by some apparently large insect flying against his window, and 
on opening the same he was disappointed in seeing that it was only a 
specimen of this Harpalus -which %vas noiv quietly resting on the window 
sill in the bright glare of the electric light near by. While looking at the 
specimen he distinctly heard the stridulating noise, and at the same time 
he plainly saw that the noise was produced by the beetle moving its abdo- 
men up and down against the inner edge of the wing-cases. 
In view of this observation the reason of the failure of both Mr. Smith's 
and my own efforts to hear the stridulations in H caliginosus becomes at 
once apparent ; for we expected to hear the noise while handling the speci- 
mens, and from our experience we were correct in stating that the Harpalus 
does not stridulate while being so handled. In Coleoptera sound-produc- 
ing apparatus are generally but little developed, but occur in several widely 
different families. They are present in Carabidce, Dytiscidce, Hydro- 
philidce* Lucanidce, Scarabceidce, Chrysomelidce, Curculionidce and Au- 
thribidce. In each of these families, and no doubt also in others, we find 
a smaller or larger number of genera, or single species, which possess 
stridulating powers. But, in all these stridulating Coleoptera the sound is 
always heard when the specimen is handled, or when it feels approach- 
ing danger, or when it is otherwise in a state of unusual excitement, e. g., 
during the act of copulation. Our Harpalus caliginosus appears to make 
