284 
Acanthia lectidaria 
well as a “ brush ” formed of many fine bristles. These “ brushes,” 
which are never seen on an immature specimen, may be cleaning organs 
of some sort, but it seems quite as likely that they help the bug to 
attach itself to rough surfaces. (It is very difficult to shake a bug out 
of a paper pill-box, an effect possibly due to the presence of these 
“ brushes.”) The abdomen is supplied with both kinds of bristle, the 
simple being on the under surface and in the middle line. In the 
female the anal segments have a preponderance of the simple with 
very few serrated, while in the male the numbers of the two kinds are 
about equal. 
The shape of the head is best seen in the accompanying sketches 
(Figs. 3 and 4) taken dorsally and also laterally. On either side of the 
median prominence, from which the rostrum rises, are the antennae, 
composed of four joints. The first is short and stumpy, rising 
from a slight knob, called by Douglas and Scott the antenniferous 
process, situated midway between the median prominence and the eye. 
The second is long and rather thicker at the apex than at the base. 
In length the third joint equals the second, but is rather more slender, 
and the chitin is much thinner, while the fourth joint, about two-thirds 
the length of the second, is slightly clavate at the apex. A very notice¬ 
able point about the antenna is that, although composed of only four 
joints, it has a great range of movement, due to the nature of the 
articulations which give the effect of a double ball and socket joint 
(Fig. 5). The end of each joint taking part in any articulation, is 
slightly narrowed and hollowed out. Connecting these two sockets is 
a short chitinous cylinder which has very free movement in each, and 
thus the antenna having three such articulations can be moved in any 
direction. As already mentioned, they are well siipplied with bristles 
of the two kinds. The presence of only simple bristles od the two 
slender apical joints, would suggest that their function is sensory, 
although the presence of similar ones on the ventral surface of the 
legs can hardly be explained on this ground. The rostnxm of the bed 
bug (Figs. 3 and 6) is a three-jointed grooved organ which, in life, is 
usually pressed up against the ventral surfaces of the head and thorax, 
these being grooved to receive it. Morphologically it is the labium 
elongated to form a projecting sheath for the mandibles and maxillae 
found in the groove running down the length of the rostrum. The 
position of this groove is such that were the proboscis to be projected 
horizontally forward, it would lie on the dorsal surface of the 
organ. As with the rest of the body surface, the rostrum is plentifully 
