1913] Anatomy of the Squash Bug. 429 



within the labrum, whose edges meet beneath and confine the 

 setas (PL LVI, f. 8 s. and PI. LVI, fs. 21-24's). They then pass 

 back through the articulating membrane, which lies between the 

 labrum and clypeus, and between the lateral walls of the clypeus. 

 The walls of the clypeus at its tip, turn under, and their edges 

 interlock forming a narrow pair of supporting lobes above which 

 the set^ pass. Upon emerging from these lobes the maxillary 

 seise (m) spread apart to receive the tip of the pharynx and the 

 canal from the salivary pump, both of which enter the setae at 

 this point. 



The setae represent the mandibles (md) and the maxillas (m) . 

 The maxillae are fluted and interlocked so as to form two tubes, 

 these being the upper or suction canal, and the lower or salivary 

 canal (PL LV, f. 2). The mandibles are slightly shorter than the 

 maxillae and their tips are barbed. Their function is that of 

 piercing the plant tissue and holding the setae in place, while the 

 tips of the maxillae, which are acute and fluted, probe the plant 

 tissues, take up the plant juices, and eject the saliva. The 

 setae, as stated, pass back into the head capsule and separate 

 at their junction with the pharynx, going to either side of it. 

 Their bases widening out form points of attachment for the con- 

 trolling muscles. 



The antenna (ant) are composed of six segments. The 

 third and fifth are ring joints (PL LVII, f. 16, r.), or reduced 

 segments; therefore the antenna as a whole appears to be com- 

 posed of only four segments. The fifth segment, or second ring 

 joint, allows great freedom of motion to the terminal segment. 

 The second and fourth segments are long and slender. The 

 proximal segment is called the scape or radicula (sa). It is 

 large and has a stalked base, which enlarges at its connection 

 with the head to form a universal joint. The terminal segment 

 is. spindle shaped and covered with numerous sensory hairs. 

 The other segments possess sensory hairs, but not as specialized 

 as those of the terminal segment. 



The compound eyes (e) are large and composed of many 

 facets, and project prominently from the head. The ocelli are 

 two in number. 



The posterior portion of the head or the coUum is set into the 

 collar of the prothorax and is joined to it by a membranous neck. 



