The commonest species about Sydney is _Atalophlebia australasica_, a small chocolate brown insect marked with black; the wings are vitreous with black markings on the veins, the front margin tinged with umber brown on the cross veins. It was described by Pictet in his “Natural History Neuroptera” (1843–45): Walker has described another from Tasmania: Eaton three more from different parts of the mainland: and Burmeister one in his “Handbook of Entomology” as far back as 1839. The members of this genus have a wide range from South America through Africa, Japan, and Ceylon. A single species of the Genus _Coloburiscus_ has been described from Melbourne. The chief work on these insects is Eaton’s “Revisional Monograph of Recent Ephemeridae or May-flies,” Parts I.-V. (Transactions of the Linnean Society 1883–87;) in this work he subdivides them into three groups containing 55 genera and 270 species. Family 4. Alder Flies and Snake Flies. SIALIDAE: This small division contains two groups that Westwood treated as two distinct families, the _Sialidae_ and the _Raphidae_; but Sharp points out, that in general structure and habits they are very closely related to each other,--the latter chiefly differing from the former in the remarkable elongation of the prothorax, and he thus only ranks them as sub-families. The Alder Flies have two pairs of broad wings, wide at the base, the hind pair slightly smaller and capable of being folded behind; they are all traversed by numerous veins forming irregular cells. They are slow in their movements, and are to be found clinging to bushes in the vicinity of water. Our commonest species is the _Chauliodes guttatus_, described by Walker; it is a large, dull brown insect with an elongated thorax and body; the head is furnished with long, slender, annulated antennae, large prominent eyes on the sides, and three ocelli on the summit. The wings are semiopaque, the fore pair finely spotted with black, thickest on the front margin; the broader hind pair are only lightly spotted at the extreme tip, with from 4 to 5 larger rounded spots about the centre. It measures over 3 inches across the outspread wings, and 1¼ inches from the head to the tip of the abdomen; it has a wide range from Victoria to Queensland. The larvae are remarkable for having fringed filaments on the sides of the abdomen; they crawl about in the mud or among the weeds in water-holes, and are carnivorous, feeding upon other aquatic insects; when ready to transform, the pupae come out of the water and crawl under stones, or sometimes under the loose bark on tree trunks.