| OCR Text |
Show 1903.] GEOGRAmiCAL DISTRIBUTION OF SPIDERS. 359 that region after the separation of Madagascar, and except that they have left isolated genera in Indo-Malaya. The Aporoptychi arose in Africa from the Cyrtauclienii before the severance of that country from South America. The Actinopodidae were perhaps evolved from an Aporoptychus-like form in South America, and crossed thence to Australia. The Migidae probably originated in the Ethiopian Region before the isolation of Sokotra and Madagascar. The similarity between the South-African and Novo-Zelandian, the Tasmanian and Patagonian genera suggests that the migration of the family from its hypothetical home took an eastward direction. The Ctenizidae, a specialised northern offshoot from the Cyrtauchenii, crossed during the Tertiary period from Asia to North America, and occur at the present time in the Sonoran and Mediterranean Regions. It entered South-eastern Asia after the separation of Australia; and Africa after the formation of the Mozambique Channel, but before the sinking of the connecting land with South America. In late Tertiary times the union of North and South America admitted the Sonoran and Mediterranean genus Pachylomerus into the Neotropical area, where it mingled with the Idiopine element that had come from Africa. The Halonoproctidse must similarly have crossed from America to Asia, or vice versa, during the Tertiary Period, since the existing genera persist at the present time in the Sonoran Region and China. It is impossible to determine the original home of the Bary-chelidse. Possibly the family originated at an early date in Africa, and became distributed all over the area they now inhabit from that centre. Possibly it arose in the northern parts of the Old World, and at an early date extended southwards into the Ethiopian, Oriental, and Australian Regions. However that may be, there seems no reason to think that the group entered the Neotropical Region from the Sonoran. The Aviculariidse arose in the northern portion of the Old World, whence emigrants passed into the Oriental and Ethiopian Regions. From one primitive type in India sprang the Thrig-mopoeinse; from another in Indo-Malaysia the Ornithoctonina?; and from a third the Selenocosmiinae, which distributed themselves from India, Ceylon, and the Philippine Islands into Australia, perhaps in Eocene times. In the Ethiopian Region, from a primitive type arose the Eumenophorina?, at a sufficiently early date to reach Sokotra, S. Arabia, and Madagascar. Later on, after the severance of Madagascar, arose the Harpactirinse. The genera of these specialised subfamilies probably supplanted to a large extent both in the Ethiopian and Oriental Regions the Avicu-lariinse, but the latter attained an enormous development in South America, which they seem to have reached from Africa or possibly from Europe. With the Pliocene union of North and South America certain forms spread northwards from South America into the Sonoran Region. |
