The Genus _Acantholepis_ is represented by four species all described by Forel from specimens I have collected and sent him from N.S. Wales, so that their range seems to be restricted. They are all small, reddish brown, smooth, shining ants; _A. bosii_ was found under stones at Cooma, N.S.W. The Green Tree-ant, _Oecophylla smaragdina_, found in tropical Africa, India, and New Guinea, is common in the tropical scrubs on the coast of North Queensland. They live in large communities among the foliage of the trees, in nests formed by webbing the leaves together into an irregular mass varying in size from a cricket ball to a man’s head. The material with which they make these nests is obtained by the workers, by squeezing the pupae and using the secretion they discharge. The winged female measures nearly ¾ of an inch in length, has a broad thorax and large oval body; the worker is only about ¼ of an inch, and slender in proportion, but for his size is the most pugnacious creature in the insect world; if one damages a nest pushing through the scrub, down tumble a swarm of green tree ants on one’s head and neck, and wherever they drop they stick their jaws in and hang on, and each one has to be picked off in detail. In these forests they destroy an immense number of insects, catching the little bees as they come out of their nests in the tree trunks, and dragging the small beetles off the twigs by main force. I have often seen half a dozen hanging on to the legs of a stout weevil, apparently trying to wear him out, for they would remain for hours in the same position, and probably succeeded in the end. The great Genus _Camponotus_ contains about 400 described species from all parts of the world, of which about 60 are recorded from Australia. Most of them are found in open forest country, forming their nests in the ground, under logs or stones, or near the butts of trees. Several of our common species are known as “sugar ants,” as they come about at night and invade the pantry and store room in search of sweets; but they are omnivorous in their tastes, and will often come round the camp fire at night, prowling about for the small moths that flutter round, often rushing right into the edge of the ashes to capture a moth when it falls with singed wings. _Camponotus intrepidus_ is one of our largest species, varying from black to reddish brown in tint, and is thickly clothed with short hair. They form nests in the open sandstone country about Sydney, sometimes raising a little mound or producing a fragile funnel-shaped structure above the opening leading into the nest. The Sugar Ant, _Camponotus nigriceps_, is the commonest house species; it forms large chambers under stones or logs in which they all cluster together. The general colour is black, with all the abdomen except the base dull yellow, but the variations of the yellow and black are common; it measures to ¾ of an inch in length.