1913] Anatomy of the Squash Bug. 433 



epimeron, episternum and sternum anteriorly, and posteriorly 

 by the anterior margin of the metastern'um and metcepisternum. 



Metathorax. — The notum of the metathorax is well developed 

 and is composed of three sclerites. The prescutum (psc), 

 which has already been described, forms the posterior wall of 

 the phragma between the meso and metathorax, and in its 

 normal position is only slightly visible from the exterior. The 

 scutum (sc) and scutellum (set) are fused and the visible por- 

 tions appear as an elongate triangular sclerite on either side of 

 the mesoscutellum which hides the middle portion. The 

 postscutellum (psct) lies behind this sclerite and is fused with 

 it, its central portion being hidden beneath the projecting 

 mesoscutellum. 



The pleuron (pi) is partially divided by the coxal cleft into a 

 large epimeron or pleurum and a very small episternum, the 

 latter being indistinguishably fused with the sternum. At the 

 upper end of the cleft lie the two light yellow scent glands (sg) 

 separated by a pit which extends into the body cavity and into 

 which flows the fluid secreted by the glands. Lying above the 

 scent glands and hidden in the folds between the meta and meso- 

 thorax is the metathoracic spiracle. On either side of the dorsal 

 margin of the metapleuron is a longitudinal grooved area called 

 the cenchrus (PI. LV, f . 4, cc and PI. LVI, f . 10, cc), in which there 

 lies a ridge, located on the ventral side of the costal margin of 

 the fore wing. 



The hind wings or alse (hw) are joined to the metathorax 

 although their bases appear to lie mostly above the mesopleuron 

 when viewed laterally. Their bases articulate with the fused 

 scutum and scutellum, whose posterior margin is continuous with 

 the posterior margin of the wing. The alae articulate with the 

 metanotum by means of numerous small chitinous plates called 

 ossicula or axillaries. 



The wing is wholly membranous and distinctly veined. The 

 venation given is the purely systematic one. The costa prima- 

 ria (ca-p) is the large vein lying just posterior to and parallel 

 with the costal margin in the basal half of the wing (PI. LVIII, 

 f. 20). The costa subtensa (ca-s) lies below the costa primaria 

 and is more or less parallel with it. Near the distal end of the 

 costa subtensa is a short incomplete transverse vein which nearly 

 reaches the costa primaria. This is called the Hamus (ha). 

 The distal ends of the costa primaria and subtensa are connected 



