EXPLANATION OF THE PLATES. 723 



FIG. 



19. Abdomen, and part of postpectus of $. Lateral view, 



with the covers removed to show the machinery. 



20. Alitrunk. Upper side. Pentatoma. 



PLATE IX. a 



1. Alitrunk of Cossus ligniperda. Upper side. 



2. Part of ditto, to show the mesophragm. 



3. ■ Under side. 



4. Patagiaof Lepidoptera. Upper and under sides. Vol. III. 



p. 368, 539. 



5. Tegulae of ditto. Two species. Vol. III. p. 378. 



6. Prothorax of JEshna. a. The base elevated and forming 



an obtuse angle with the rest. 



7. Alitrunk of ditto. Upper side. a. Two elevated areas 



of the posterior parts of the collar, strengthened by a 

 marginal ridge and denticles, internally connected by 

 an elastic ligament, apparently to aid and sustain the 

 powerful action of the wing-muscles. 



8. ■■ Lateral view. a. A piece by which 

 the mid-leg is connected with the scapular. Vol. III. 

 p. 48, 565. 



9. Part of the abdomen of Libellula. 



10. Trunk of Semblis F. Upper side. 



11. Alitrunk of Vespa Crabro. Upper side. a. Aperture in 



the trunk for the passage of the ligament that elevates 



the abdomen. 

 J 2. Lateral view of ditto. 

 13. posterior part of ditto, and of the base of 



the abdomen, to show the above apparatus* a. The 



aperture. Vol. III. p. 701. 

 14. Head and part of the manitrunk of Tenthredo L. to show 



the membrane a. representing the prothorax. Vol. III. 



p. 550—. 



s Vol. III. p. 367—, 529—. IV. p. 326-. 

 3 A 2 



