OCR Text |
Show 1 9 0 3 . ] GEOGRAPHICAL DISTRIBUTION OF SPIDERS. 3 4 5 as well as to the South-American and Afro-Mascarene forms, points equally forcibly to the peopling of Australia from either one or the other, or perhaps both, of the southern continents just mentioned. The remaining genera of Diplurime, namely, Trechona, Diplura, Harmonicon, Melodeus, and Uruchus, all of which are more specialised types than Brachythele and its allies, probably arose within their present area of distribution. A great contrast to the distribution of the Diplurinse is presented by that of the Macrothelinse. The occurrence of Macrothele in Spain, China, Burma, and Java ; of Porrhothele, which is scarcely separable from it generically, in New Zealand; of Phyxioschcerna in the Transcaspian area; and of its near ally, Stenygrocercus, in Queensland and New Caledonia, suggests a southward migration of these types from the northern provinces of the Old World into Australia and New Zealand by way of China and Indo-Malaysia. Similarly Ischnothele, a more specialised type than Macrothele, perhaps descended from the north by way of India into Madagascar, South Africa, and crossed thence into South America, where with Evagrus, which is also represented in South Africa, it is the only representative of this group of Dipluridre. The entire absence from the Sonoran Region of forms related to Macrothele, Evagrus, and Ischnothele, is opposed to the supposition that the two last-mentioned genera had a northern origin in America. The Masterise appear to be degenerate forms of the Macrotlielae. They are the smallest of all known Mygalomorplise, and are essentially cryptozoic or lucifugous, living in caverns or under old decaying vegetation in the dark, damp forests. Hence we can only pretend to a partial knowledge of their distribution, and it would be rash to draw deductions from the fact of their having been discovered hitherto only in Venezuela, the Philippines, and Upolu. The two genera of Atraces, Atrax and Hadronyche, confined to Australia, appear to be Macrothelina? specialised for a fossorial life, with which is correlated certain features imparting to them a superficial similarity to the Ctenizidas. The Hexathelae, resembling the Macrothelae except in the retention of an additional pair of spinning-mamillae, undoubtedly a primitive feature, are confined, so far as is known, to New Zealand and Chili. There seems no reason to doubt that they passed from one of these countries to the other by a southern land-connection. Family P ar a tr o p id .e . This family, specialised both in structure and habits, is represented by three genera, Paratropis, Anisaspis, and Anisaspoides, confined to the Neotropical Region. Its affinities are doubtful, but some primitive genus of Dipluridse allied to Brachythele must |