896 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXVIII. 
Anisoptera have the fore and hind-wings unequal, the base of the hmdwing 
being with rare exceptions much broader than that of the fore. The eyes, ex- 
cept in one family — the Gomphince, are always more or less in contact with one 
another. 
Zijgoptera have both wings of the same shape, the hind in- some species may be 
broader but the base is invariably narrow. The eyes are invariably separated. 
For further classification it is necessary to master a few terms which with very 
little mental effort one soon grows accustomed to. 
The venation of the wings forms the main basis of classification, .so must be 
studied in particular. 
1. The Wing. 
The foreborder of the wing is called the “ costa,” the hind, the “ termen.” 
The part nearest the body, the “ base,” and the part most remote, the “ apex.” 
Near the apex, on the costa will be seen a small opaque, thickened part, varying 
in shape, sometimes long and narrow, sometimes nearly square, rarely in one of 
the sexes (female) absent altogether. This is called the “ pterostigma.” The 
3 
Fig. 3.— A. Wing of an Anisoptera. B. Wing of a Zygoptera. (Only the 
base is shovTi.) 
1. Pterostigma, 2. Postnodal nervures, 3. Costa, 4. Node, 5. Antenodai 
nervures, 6. Arc, 7. Sectors of arc, 8. Trigone in the Anisopterous wing. 
Quadrilateral in the Zygopterous, 9. Cubital nervure (known as ac.). 10. 
Median or arcular space, 11. Cubital space, 12. Anal triangle, 13. Loop, 
14. Tomus or Anal angle, 15. Base of wing, 16. Termen or posterior border 
of wing, 17. Apea: of wing, 18. Radius, 19 Mi, 20. MU, 21. Rs or Radial 
sector, 22. Rspl. or Radial supplement, 23. Miii, 24. Miv, 25. Mspl or 
supplement to Miv, 26. Cui, 27. Cuii, 28. Bridge, 29. Membrane. 30 Anal 
bridge (known as ab.) 
nervures are best learnt from a study of the text figure (Fig. 3) but the .spaces at 
the base of the wing must be noted. A well marked triangle will in particular be 
noted in the Anisoptera which is known as the “ trigone.” 
The space immediately above the trigone is called the “ hypertrigone,” whilst 
the space below and behind it is the “ subtrigone.” The upper border of the 
