There have been many schemes of classification and sub-divisions of these insects proposed by various authors, and the present idea among specialists seems to tend to a still closer definition of the families, as exemplified in Ashmead’s recent Classification running through the pages of the Canadian Entomologist; but in a book of this kind, I can only deal with the most important divisions and refer my readers to the work of such specialists. Westwood divided the first section, _Terebranti_, in which the females are provided with a more or less projecting instrument for depositing their eggs, into two sub-sections, _Phytiphaga_, in which the abdomen is sessile, and _Entomophaga_, in which the body is stalked. Some of the French entomologists had previously suggested dividing them up into five large families defined by the peculiarities of the ovipositor or borer. Kirby used the same terms as Westwood, but I have followed Sharp, who uses the names _Sessiliventres_ instead of the first, and _Petioliventres_ for the second, for they certainly express more clearly the form of the body of the groups under observation. The first group contains four families. Family 1. Stem-Sawflies. CEPHIDAE. The first group comprises what Sharp terms “Stem-Sawflies,” which are not represented in Australia. They are slender little insects with long antennae; the larvae feed in the stems of plants; one damages wheat stems in Europe, another infests willows in America, a third is recorded from Japan; but they are unknown in Australia. [Illustration: Plate X.--HYMENOPTERA. Family TENTHREDINIDAE. 1. _Phylacteophaga eucalypti_ (Froggatt). 2. _Phylacteophaga eucalypti_ (Froggatt), Larva. 3. _Perga dorsalis_ (Leach). 4. _Perga dorsalis_ (Leach), Larva. 5. _Perga lewisii_ (Westwood).] [Illustration: _Plate X.--HYMENOPTERA._] Family 2. ORYSSIDAE. This family consists of the single Genus _Oryssus_, of which only 20 species are known. They are remarkable for the curious situation of the antennae on the under-surface of the head, the cylindrical rounded abdomen, and the exposed needle-like ovipositor. Turner has described one from Mackay, Queensland, in the Proceedings of the Linnean Society N.S.W. under the name of _Oryssus queenslandicus_. It is a small black insect measuring ½ an inch in length; with mottled brown wings, and typical shape of the genus. Family 3. SIRICIDAE.