372 EXTERNAL ANATOMY OF INSECTS. 
inner margins of the two Elytra, where when closed 
they unite longitudinally ?. 
C. Epretrura (the Epipleura). The inflexed accessory 
margin observable underneath in many Elytra, 
which covers the sides of the alitrunk and abdomen?. 
D. Auta (the Winglet). A small, membranous, wing- 
like appendage, attached to the Elytrum on one side 
and the Frenum on the other; which probably 
serves to prevent the dislocation of the former °.— 
Ex. Dytiscus. N.B. A similar organ for a similar 
purpose 7s to be found in Blatta and the Diptera. 
FE. Hypopverma (the Hypoderma). The skin, in some 
species beautifully coloured, that lines the Elytra 4. 
N.B. This skin ts also found in some Hemelytra, but 
not in ‘Tegmina. ) 
c. Tremina (the Tegmina). The upper organs of flight, 
when of a uniform coriaceous or pergameneous tex- 
ture, veined with nervures, and lapping over each 
other ¢.Ex. Orthoptera ‘.- 
d. Heme ytra (the Hemelytra). The upper organs of 
flight, when they are corneous or coriaceous at the 
base and membranous at the apex ®.—Ex. The 
heteropterous Hemiptera. They include the Corium 
and Membrana. 
A, Corium (the Corium). The corneous or coriaceous 
part of the Hemelytrum *. 
> Prats X. Fic. 1. c’”’. > Prate XXVIII. Fic. 6—8. d’”. 
© Prate XXIII. Fic. 6.e”. ¢ Prate XXVIII. Fic. 2. a”. 
© Ibid. Fic. 19. and X. Fie. 2. 
‘ 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 Al@ Superiores. 
8 Plate X, Fic. 3. n Tbid. f’”’. 
