378 EXTERNAL ANATOMY OF INSECTS. 



vex scales, which in many Orders, particularly Hy- 

 menoptera, cover and defend the base of the Upper- 

 Wings a . 

 D Scutellum (the Scutcllum). A piece, visually tri- 

 angular, which follows the Dorsohmi; and in Co- 

 leoptcra is often only a continuation of it — placed 

 between the base of the Elytra or upper- 

 wings b . 

 E Frgenum (the Frcenum). A piece that lies under the 

 lateral margin of the Scutellum and Dorsolum, or is 

 adjacent to it; and which in many cases connects 

 with the base of the upper organs of flight, so as to 

 prevent their dislocation, by being pushed too far 

 outwards . 

 F Pnysteg a (the Pnystega). A corneous scale or plate, 

 which covers certain pneumatic vessels, usually 

 supported by the Scapularia, in Libellulina, &c. be- 

 coming dorsal d . 

 1. Medipectus (the Mid-breast). The underside of the 

 Jvrst segment of the alitrunk e . It includes the 

 Peristethium, Scapular ia, Mesosternum, Medifurca, 

 and Pedes Inter medii. 

 A Peristethium (the Peristethium). The anterior 

 piece of the Medipectus, which intervenes between 

 the Brachia and mid-legs f . 

 B Scapularia (the Scapulars). Two pieces, one on 

 each side the Medipectus, which succeed the Peri- 

 stethium, and lie between the midlegs and the Pte- 



■ Plate IX. Fig. 5, 11. g" . * Plates VIII. IX. XXVIII. k\ 



c Ibid./'. d Plate IX. Fig. 7. m l . 



e Plate VIII. Fig. 4, 13, 17.; and IX. Fig. 3, 8, 12. d. 

 f Ibid, ri. 



