After excising the families usually treated as _Pseudo-Neuroptera_ from this order, these insects can be defined as the “lace wings,” furnished with two pairs of delicate gauzy wings reticulated with a network of fine transverse and parallel veins forming a great number of more or less irregular cells. The head is furnished, with a few exceptions, with stout jaws adapted to their carnivorous habits; large eyes; and antennae of many different forms, sometimes short, thickened, or clubbed, but in others long, slender, and filiform. The legs, suited to their clinging habits when at rest, are generally slender, and the body more or less elongate. Most of them undergo a complete metamorphosis; the active larvae are furnished with large sucking or biting jaws; in the terrestrial forms they live among foliage or on the ground, and feed upon aphids, mites, ants, &c., and when full grown pupate in regular cocoons. While some of the aquatic forms go through a pupal stage in cells in the mud or under stones, others, like the dragon flies, have no true pupal form, simply going through a series of moults, and changing from an aquatic life to an aerial one by crawling out of the water and emerging from the pupal case, leaving it attached to the water plant. Sharp places the Neuroptera in eleven families, further divided up into a number of sub-families under five tribes. In excising the _Pseudo-Neuroptera_ seven families remain, though the _Hemerobiidae_ includes a number of sub-families that by some writers are ranked as families. The Neuroptera are represented in Australia by many very handsome and curious insects, of which the dragon flies are probably the most typical and well known. Family 1. Stone-flies. PERLIDAE. The Stone-flies are not an extensive group, and though the European and American forms have been studied, very little is known about our species. In England several species are much prized by fishermen as tempting bait for fly-fishing. The perfect insects have oblong, flattened bodies of uniform width to the tip of the abdomen, terminating in a pair of long slender tails or setae. The head is long, provided with large prominent eyes, three ocelli, slender thread-like antennae, and weak mouth parts; the fore-wings are slightly longer than the hind ones, which are very broad and folded down the middle when closed. They are generally found about watercourses in early summer, and lay an immense number of eggs (5,000 to 6,000 some authorities state are laid by each female); these eggs are dropped on the surface of the water. The larvae are very like the perfect insects except that they have no wings; they are active carnivorous creatures living in the bottom of swift running streams, crawling under the stones, and feeding chiefly on the larvae of mayflies.