_Monomorium pharaonis_ is our tiny red house-ant introduced from Europe, now world wide in its range; and when once it becomes established in a house is a difficult pest to destroy. _M. rubriceps_, a much larger species but under ¼ of an inch in length, is bright reddish brown, with the nodes very small and the apical portion of the abdomen black, and broadly rounded. It is found crawling upon the trunks of trees, and has a wide range from Sydney to Cape York. The typical tree-trunk ants included in the Genus _Podomyrma_ are much larger ants, sluggish in their habits, forming their nests in tree stems and always found crawling about the trunks. They are broad-headed ants with short stout jaws toothed at the tips; the thorax is widest in front, tapering to the narrow pedicle of the broadly rounded abdomen; the thighs of the legs are thickened in the centre. _Podomyrma gratiosa_, under ½ an inch in length, is bright reddish brown, rugose and spined on the front margin of the thorax, with the abdomen black, smooth, and shining; it is widely distributed over Australia from Adelaide to Cape York. _P. adelaidae_ is a smaller species with black legs, and a distinct oval brown blotch on either side of the black abdomen; it is common in South Australia and Victoria. _P. bimaculata_ is still smaller, with the blotches on the abdomen smaller and more oval; I have had it from Kalgoorlie W.A., and Wagga N.S. Wales. [Illustration: Plate XIV.--HYMENOPTERA. Family FORMICIDAE. 1. _Iridomyrmex detectus_ (Smith). 2. _Polyrhachis semi-aurata_ (Mayr). 3. _Myrmecia gulosa_ (Fabr.). 4. _Ectatomma metallicum_ (Smith). 5. _Iridomyrmex rufoniger_ (Lowne). 6. _Camponotus nigriceps_ (Smith).] [Illustration: _Plate XIV.--HYMENOPTERA._] The Genus _Pheidole_ is well represented in Australia by 22 species and many varieties found in all parts of the country, forming irregular chambers and galleries under stones and logs; they are tiny reddish brown ants, with a very large headed form of soldiers often four or five times the size of the ordinary workers. The winged forms are also very large in proportion. _Pheidole bos_ is dark reddish brown, the soldiers furnished with very large swollen heads; it ranges from Western Australia to Victoria. _P. anthracina_ is a darker coloured form, ranging from the northern portion of N.S. Wales into Queensland. The members of the Genus _Cremastogaster_ are very small black, brown, or dull yellow coloured ants with longer legs, and heart-shaped bodies; they live in large communities in nests under logs and stones. _C. fusca_ is black with reddish tarsi, and a reddish tint on the thorax; it comes from Queensland. _C. pallipes_ and _C. ruficeps_ are lighter coloured, found under stones about Sydney.