_Discontinuous generic Areas._--It is not very easy to find good examples of genera whose species occupy two or more quite disconnected areas, for though such cases may not be rare, we are seldom in a position to mark out the limits of the several species with sufficient accuracy. The best and most remarkable case among European birds is {24} that of the blue magpies, forming the genus Cyanopica. One species (_C. cooki_) is confined (as already stated) to the wooded and mountainous districts of Spain and Portugal, while the only other species of the genus (_C. cyanus_) is found far away in North-eastern Asia and Japan, so that the two species are separated by about 5,000 miles of continuous land. Another case is that of the curious little water-moles forming the genus Mygale, one species _M. muscovitica_, being found only on the banks of the Volga and Don in South-eastern Russia, while the other, _M. pyrenaica_, is confined to streams on the northern side of the Pyrenees. In tropical America there are four different kinds of bell-birds belonging to the genus Chasmorhynchus, each of which appears to inhabit a restricted area completely separated from the others. The most northerly is _C. tricarunculatus_ of Costa Rica and Veragua, a brown bird with a white head and three long caruncles growing upwards at the base of the beak. Next comes _C. variegatus_, in Venezuela, a white bird with a brown head and numerous caruncles on the throat, perhaps conterminous with the last; in Guiana, extending to near the mouth of the Rio Negro, we have _C. niveus_, the bell-bird described by Waterton, which is pure white, with a single long fleshy caruncle at the base of the beak; the last species, _C. nudicollis_, inhabits South-east Brazil, and is also white, but with black stripes over the eyes, and with a naked throat. These birds are about the size of thrushes, and are all remarkable for their loud, ringing notes, like a bell or a blow on an anvil, as well as for their peculiar colours. They are therefore known to the native Indians wherever they exist, and we may be the more sure that they do not spread over the intervening areas where they have never been found, and where the natives know nothing of them.