EXTERNAL ANATOMY OF INSECTS. 373 



C Epipleura (the Epipleura). The inflexed accessory 

 margin observable underneath in many Elytra, 

 which covers the sides of the alitrunk and abdo- 

 men a . 



D Alula (the Winglet). A small, membranous, wing- 

 like appendage, attached to the Elytrum on one side 

 and the Frcemim on the other ; which probably 

 serves to prevent the dislocation of the former b . — 

 Ex. Dytiscus. N. B. A similar organ for a similar 

 purpose is to be found in Blatta and the Diptera. 



E Hypoderma (the Hypoderma). The skin, in some 

 species beautifully coloured, that lines the Elytra c . 

 N. B. This skin is also found in some Hemelytra, but 

 not in Tegmina. 



c Tegmina (the Tegmina). The upper organs of flight, 

 when of a uniform coriaceous or pergameneous tex- 

 ture, veined with nervures, and lapping over each 

 other d . Ex. Orthoptera e . 



d Hemelytra (the Hemelytra). The upper organs of 

 flight, when they are corneous or coriaceous at the 

 base and membranous at the apex f . — Ex. The 

 heteropterous Hemiptera. They include the Co- 

 rium and Membrana. 



A Corium (the Cor ium). The corneous or coriaceous 

 part of the Hemelytrum s . 



a Plate XXVIII. Fig. 6—8. d'". h Plate XXIII. Fig. 6. e". 



« Plate XXVIII. Fig. 2. a'". 



d Ibid. Fig. 19. and Plate X. Fig. 2. 



e The upper organs of flight of many of the homopterous section 

 of the Hemiptera seem altogether membranous, and may almost be 

 included under the term Alee Superiores. 



f Plate X. Fig. 3. E Ibid./'". 



