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POPULAR SCIENCE REVIEW. 
Fig. 6. Dorsal surface of Blow-fly. 
Fig. 7. Ditto of Cockroach. These two figures are introduced to illustrate 
the difference of structure between the Metabola and the Hetero- 
metabola, the prevalence of the regional distinction in the one, and 
of the segmentary division in the other. In the former, the whole 
of the central division of the body here visible consists of the meso- 
thorax, with the exception of the anterior angles, which belong to 
the prothorax. 
Fig. 8. The metathorax of the Stag Beetle, dorsal surface ; prs", the 
prsescutum ; w, the attachment of the wings ; g, membranous 
continuation of ditto ; sp, sp, spiracles of fifth and sixth segments ; 
5, dorsal plate of fifth or ventrally atrophied segment, the thoracico- 
abdominal segment of Newport. The remaining letters as before. 
Fig. 9. Ideal diagram of an insect segment after Packard ; dp, dorsal plate ; 
lp, lp, lateral plates ; vp, ventral plate ; aa, dorsal appendages, the 
wings; aa, ventral appendages, the legs; ac, alimentary canal; 
ng, nervous ganglia ; dv, dorsal vessel ; tr, tracheae ; sp, spiracle. 
Fig. 10. Lateral view of mesothorax and following segments of Stag 
Beetle ; 11, lateral plates of abdomen ; vp, ventral plates of ditto. 
The remaining letters as before. 
Fig. 11. The wing unfolded ; a, the point where the fold occurs. 
Fig. 12. Abdominal spiracle, internal view, open; a, the aperture between 
the valves ; h, the handle ; m, its muscle. 
Fig. 13. Ditto, closed. 
Fig. 14. Ditto, external view. 
Fig. 15. Maxilla ; Is, the fringed superior lobe ; p, the palp ; st, stapes ; 
li, inferior lobe ; lac, lacinia ; car, cardo. 
Fig. 16. Labium ; lig, ligula ; par, paraglossae ; p', palp. 
Fig. 17. Tarsus of posterior leg. 
Fig. 18. Branching processes of abdominal spiracle. 
Fig. 19. Transverse section of ditto; m, the margin; p, processes; a, the 
aperture ; h, the handle. 
