The genus ANDRENA, although infinitely more numerous in species than the genus _Halictus_, which is also abundant, does not appear to have so wide a distribution as the latter. Peculiarities of habits possibly limit its diffusion, although nothing has occurred to naturalists to explain the circumstance, unless it be the adventitious fact of no specimens having fallen into the hands of the collector. Our own species, represented by one or several members, are found (although some seem restricted to England) throughout Europe, north and south, east and west, as also in its islands. In Africa it is seen in Algeria and Egypt, and it occurs in the Canaries; and in Asia it is found in Siberia, and in northern India; but we have no connecting chain to link those Asiatic and African localities,—although we may well suppose that it might be discovered amongst the steppes of Thibet and Tartary, revelling amidst the flowers of their luxuriant pastures, and even amongst the Persian sands. It passes through the United States from Florida up and to our own colony of Nova Scotia, and extends its range to Hudson’s Bay. We do not trace it further. Nearly two hundred species occur. The genus CILISSA, too, has a limited distribution, and occurs in the same countries, but ranges as high as Lapland; it also crosses the Atlantic, being found in the United States. About six are known. Our solitary species of the genus MACROPIS, which is isolated possibly only from having been overlooked, appears to have but a European existence, and is found in France, Germany, Denmark, Sweden, and Finland. The genus HALICTUS is very cosmopolitan. Some of our own species occur throughout Europe, excepting only Italy and Sicily, although they are to be found in Portugal and Dalmatia, thus traversing its entire breadth; but from the latter country they do not seem to range down to Albania and Greece, yet are they discovered in Malta, and even in southern Africa, but they have not been recorded as extant in northern portions of that continent. Other species have been sent from the western coast of Africa and the adjacent Canaries, with their adjunct, Madeira, and the genus ranges from Barbary through Senegal and Sierra Leone; some species also are found at the Cape of Good Hope.