The AGRIONIDAE are the delicate slender-bodied dragon flies with oar-shaped wings, and narrow heads with the eyes standing out on either side. _Lestes analis_ is our common type of the large genus; it is of the usual slender form, with the body nearly as long as the expanse of wings, and is of a general reddish brown colour. _Synlestes weyersii_ is a very beautiful slender creature nearly 3 inches across the wings, and over 2 inches from the front of the head to the tip of the body. It has transparent wings with an oval whitish pterastigma toward the tips, and the whole head and body is deep rich metallic green. It flies in a very graceful manner up and down the edges of the watercourses, resting every now and then on a reed or overhanging twig, and is very easily captured. _Ischnura heterosticta_ is our tiny, little, banded, blue and brown dragon fly, with the female of a more sombre brown tint: Tillyard has recorded two forms of females in this species, one taking on the garb of the bright-coloured male. _Ischnura delicata_, very similar in size and form, has the basal two-thirds of the abdomen red and the apical portion blue. The larvae of both these species are common in the ponds about Sydney in the early summer. Tillyard (Pro. Linn. Soc. N.S.W. 1905) has recently added three new species of the Genus _Austrogomphus_ collected in the Cairns district N. Queensland. Family 3. May-flies. EPHEMERIDAE. These delicate gauze-winged insects were named Ephemera from the old idea that their life as perfect insects lasted only for a day; they were born in the morning and died at the fall of day. Though their span of life is short, as they possess only rudimentary mouths incapable of absorbing food, and only live a short time after the eggs are laid, it is generally a matter of a few days. They have large prominent eyes; three ocelli; and minute antennae consisting of two thickened joints surmounted with a needle-like hair or bristle: the prothorax is small, the middle portion large; and the somewhat small body, generally composed of ten segments, is provided with a slender articulated hair-like tail on either side. The wings are broadest at the base, rounded at the extremities, with the hind pair small, in some genera the hind pair absent. The larvae live in burrows in the mud at the bottom of ponds or watercourses, and when full grown climb up the stalks of grass or plants and cast their pupal coverings. Most of our species are only found in odd pairs, and do not assemble in swarms as they sometimes do in England; but in 1885, in the Royal Geographical Society’s Exploring Expedition in New Guinea, when ascending the Fly River we met with great clouds of the large white Mayfly, _Palingenia papuana_, flying along over the surface of the water just as described by D’Albertis in his work on New Guinea; specimens I collected are now in the Australian Museum.