hitrodiidion to Animal Morphology. 385 



{labmm), sometimes palpiferous. The united cardines 

 of this pair of maxillsB form the chin or menhwi, in 

 front of which a tongue or ligula may be formed by 

 the union of stipes, squama, and mala. These parts 

 may be modified in different ways as suctorial organs. 



The dorsal surface of each segment of an insect's thorax 

 is the pro-, meso-, or meta-notiim ; the under surface is the 

 pro-, meso-, or meta-ste7-nnm, and the sides are called phurce, 

 each of which is divided transversely into a fore {scapula) and 

 hinder piece {epimerum). The mesonotum bears a some- 

 what triangular area {scutelluni), with two lateral areas ox pa- 

 rapsides. Endothoracic projections exist at the sutures. 

 Mesially on the metanotum is the post-scutellum. Sometimes 

 the thoracic segments are closely united, or the prothorax 

 may be free {prothorax liber') ; in this case alone is it large. 

 The legs articulate in cavities (acetahula) between the sternum 

 and pleurae. The first part of the leg is the coxa, more or 

 less sunk in the acetabulum ; next follows a ring or trochanter 

 to articulate with the next joint, ox femur ; then follows the 

 tibia, often with a movable projecting spur {calcar) ; and lastly 

 the tarsus, of several joints, carrying at its end two, rarely one 

 claw, and often dermal folds between {pseiidonychia). Limbs 

 may be natatory and flattened, gressorial, fossorial, saltatory, 

 or raptorial. 



Dorsally articulated are the wings arising between 

 the notum and pleurae of the meso- and meta-thorax ; 

 that on the first is the fore-wing, that on the second 

 the hind-wing. These are flattened saccular elonga- 

 tions of the integument, whose inner walls coalesce, 

 and are separated and supported by the cosIcb of the 

 wing, consisting of branches of trachea3 with a thick- 

 ened chitinous lining, and chitinized externally. In 

 beetles, &c., the fore-wing becomes thickly chitinized, 

 loses its flying power, and becomes an elytron or wing^ 

 cover. Wings may be absent, especially in females. 



2 C 



