6 MR. R. J. TILLYARD : LIFE-HISTORIES AND 



an TEscbnine, the following characters may be said to be common to them 

 all:— 



Venation. — Triangles elongate, crossed, of approximately equal shape and 

 size in both wings ; basal side always considerably distal from arculus. 

 Antenodals of first and second series not corresponding, except two specially 

 thickened ones (usually the first, and another between the fourth and 

 eiohth). il/2 always arching up more or less under the pterostigma, so as to 

 approach ilii- Pterostigma nearly always long, generally narrow, usually 

 braced. Strong supplements developed under Ms and il/4. Membranule 

 very seldom absent. Anal border of hind-wing of male angulated (except 

 in Anax). Anal loop short and fairly broad, never elongated. 



Head. — Eyes very large, touching for a considerable distance ; conse- 

 quently postocular region much reduced to a small triangle or tubercle, and 

 vertex reduced to a vesicle or tubercle. Antennae short, with two short, 

 rather stout, basal joints, followed by five slender filiform joints. Front, 

 face, and mouth-parts well developed ; labium hairy^ with broad lateral 

 lobes carrying movable hooks, and short wide mentum. 



Thorax. — Prothorax very small, often reduced to a mere neck and a small 

 basal support for the fore-legs. Meso- and metathorax firmly united 

 together, strongly built; rostrum with very distinct but small scuta and 

 ■ scutella. Legs strong, fairly large. 



Abdomen. — Always slender and elongated, never either clubbed or swollen 

 towards tip. Auricles present on segment 2 of male (except Anax). 

 Accessory genitalia of segment 2 of male lodged in a deep median ventral 

 depression or fossa. Male with two superior and one inferior anal appendages. 

 Female with generalized ovipositor suited for placing eggs in the tissues of 

 plants, and consisting of three pairs of elongate processes, one pair developed 

 from the eighth,, the other two from the ninth sternite. 



Larva or Nymph. — General shajye elongate, with large head, prominent 

 eyes supported by strong postocular lobes ; prothorax of moderate or small 

 size often with lateral spines or tubercles ; abdomen well rounded above, 

 flatfish beneath. Antennae filiform, usually 7-jointed in the full-fed nymph. 

 Wing-cases not divergent. 



Labial Mask with flat, more or less elongated mentum ; median lobe 

 seldom projecting, often bilobed ; lateral lobes narrow, with apex either 

 pointed, rounded off or truncate, often with a tooth projecting from inner 

 apical angle ; inner border finely crenulate or smooth ; movable hook long, 

 strong, pointed ; position of hinge when at rest very variable, lying some- 

 times as far forward as the procoxse, sometimes as far back as the metacoxse. 



Anal Appendages. — The true anal larval appendages consist of a single 

 median superior appendage {appendix dorsalis of Pleymons), which is an 

 outo-rowth from the eleventh tergite, and two lateral inferior appendages 

 (the true cerci of Heymons), outgrowths from the two pieces of the eleventh 



