The members of the Genus _Bidessus_ are small, brown, boat-shaped beetles not much over ½ an inch in length; about 18 species are listed in Masters’ Catalogue; _Bidessus bistrigatus_ has the head marked with black and the wing covers clouded with dark brown; it has a wide range over Australia. _Antiphorus gilberti_ is more than twice the size, has the wing covers mottled, and is common in the waters of Victoria and South Australia. _Macroporus howetti_ is dark brown, more shining and slightly larger, the dark markings forming two irregular black bands connected by a dorsal stripe. _Hydroporus collaris_, from the north-west coast of Australia, measures under 2 lines in length; it is all black with the dorsal surface convex and finely rugose. _Platynectis 10-punctata_ was described by Fabricius at a very early date from Australia; it is common along the edges of the Murray lagoons, where it is to be found in the soft mud under the water-weeds. It is a smooth, shining black beetle, with very convex wing covers. _Rhantus pubescens_ is an oval beetle, under ½ an inch in length, of a dull brown colour, with the whole of the wing covers granulated with black. _Colymbetes lanceolatus_ is a more elongate insect of a similar brown colour, the back of the head and wing covers marked with irregular parallel black lines, thickest in the middle. _Copelatus acuductus_ is a larger shining black beetle, typical of the genus, of which about twenty species are described from this country. _Cybister tripunctatus_ is one of our largest species; it measures over 1 inch, and is broad and flattened in proportion; it is of a blackish or dark olive colour, margined right round from the front of the head to the tips of the wing covers with a dull yellow stripe. As children we often pulled these beetles out of the water hanging on to the bait used for catching crayfish, and we called them “clocks,” why I do not know. This species has a very wide range over Australia, and it is recorded from Lord Howe Island. It was once known under the name of _C. gayndahensis_. A second species has been described by Blackburn under the name of _C. granulatus_ from the Northern Territory of South Australia. _Eretes australis_ is another widely distributed species; it measures about ½ an inch; is broad and flattened, and is of a general yellowish brown tint, marked with black between the eyes, and the wing covers are finely punctured with close black spots. Family 4. Whirligig Beetles. GYRINIDAE. This family, small in number of species, is well known to all lovers of Nature, for it contains the water beetles that float about in shoals on the margin of any quiet stream or waterhole, or dart about like bits of silver, twisting and turning round in most remarkable gyrations, from which they take the popular name of Whirligig Beetles.