THE CHARACTERISTICS OF INSECTS. 



231 



second pair of wings, which are always membranous when they are 

 not atrophied, and the third pair of legs. The ventral part of the 

 thorax is called the sternum, and the lateral pieces are the epimera. 

 The wings, usually four, are sometimes reduced to two, and 

 may even disappear entirely, when the insect is said to be apte- 

 rous. The two pairs of wings, when they exist, are unlike, as in 

 the Coleoptera and bugs, or alike, as in the Hymenoptera and 

 Neuroptera. When 

 they are unlike, 

 those of the first 

 pair have a horny 

 consistency. They 

 form a protecting 

 case for the wings of 

 the second pair, and 

 are called elytra; the 

 wings of the second 

 pair are membra- 

 nous, and are sup- 

 ported only by a 

 network of nerves, 

 which forms a kind 

 of framework for 

 them. Of this char- 

 acter are the wings 

 of the cockchafer 

 and stag-beetle. In 

 the elytrum we dis- 

 tinguish the base, 

 or part adjacent to 

 the prothorax ; the 

 shoulder, or fore- 

 external part ; the 

 humeral callosity, a 

 more or less pro- 

 nounced lump near 

 the shoulder ; the 

 suture, an inner 

 part, by which the 

 elytra at rest are in 

 contact ; the humer- 

 al angle, or external 

 basilar angle (of the 

 side of the shoulder); 



the SClltellarv ano-lp ^ IO - ^ 2 - Antennae. 1. Setiform antenna. 2. Setaceous an- 



\ & ' tenna. 3. Filiform. 4. Fusiform. 5. Serrated. 6. Pectinate. 



Or inner basilar ail- 7. Flabellate. 8. Clubbed. 9. Lamellated. 10 and 11. Bent. 



