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tube connects directly with the pharynx. The mandibles and maxillae 
at their proximal ends are swollen and hollowed out for the insertion 
of their muscles (Fig. 16), called by Landois “ Musculi erectoris et 
retractoris rostri.” The chitin of the under surface of the head is 
very thick, especially in the middle line, forming, in fact, quite a ridge, 
grooved externally to hold the proboscis when not in use (Figs. 14 and 15). 
The upper surface is also thick, thus giving the strength required for 
the attachment of the muscles which work the pharynx pump, but of 
the two surfaces the ventral is the thicker. 
In the thorax of the bed bug (Fig. 18) the three main divisions of 
pro-, meso-, and meta-thorax are found, each being well developed and 
articulated to the others. Of the three regions, the pro-thorax is the least 
complex, since it consists of only the tergum and sternum. Its breadth 
is much greater than its length, and has broad leaf-like expansions of its 
chitinous covering at the sides. These run forward by the side of the 
head almost as far as the eyes. At the posterior border the sides curve 
in rather more sharply to the base line. The broadest diameter of the 
pro-thorax is at about one-third of its depth measured from the tips of 
the anterior lobes. Its surface is covered, dorsally, with bristles in their 
bowl-like sockets, while the chitin between the sockets is slightly rugose. 
The under surface is like the upper in contour and bears the coxal 
cavities, here very close together, leaving, in fact, just room for the tip 
of the proboscis. In texture the surface is similar to that of the 
dorsal with the exception of the lateral area at the base of the coxal 
cavities. Here there is a large area peppered all over with small 
pits. These special locations are for the attachment of the muscles 
of the front legs. In the middle line on the ventral surface the chitin 
of the pro-thorax is very much thickened. In fact it forms a strong 
ridge internally, whose external surface is grooved for the reception of 
the proboscis when at rest, and thus continues the line of the similar 
groove on the under surface of the head. This segment bears a pair of 
spiracles which are situated external to the coxal cavity and in the 
angle formed by it and the base line of the segment. 
Viewed from above, the meso-thorax or scutellum has the appear¬ 
ance of a straight line from whose extremities two ogee curves arise 
and meet posteriorly at a point. Having a double set of articulations, 
namely the second pair of legs and the wings (although these last 
are non-functional), this section is much more strongly built, and to 
give the necessary room for the muscles it has well-developed pleura. 
These are much indented and strengthened for the muscle attachments, 
