| OCR Text |
Show 1 9 0 3 . ] GEOGRAPHICAL DISTRIBUTION OF SPIDERS. 3 4 9 Africa; Microbcitesia in tropical W. Africa; Stictogaster, Bessici, ancl Homostola in S. Africa; Stenoterommata, Pselligmus, Neo-cteniza, Eucieniza, and Enrico in South and Central America; Aptostichus and Actinoxia in California ; and Myrmeciciphila in Virginia and Carolina. 3. Aganippae, differing from the preceding in the specialised arrangement of the eyes.-Aganippe, Blakistonia, Anidiops, Idiosonia-all confined to Australia. 4. Aporoptychi, differing from the Cyrtauclienii in the enlargement of the labium and maxillae.-Aporoptyclius and Bolo-stromus occur in tropical West Africa and South America ; Phrisscecia, Phceoclita, Celidotopu.s, Phcenothele, and Rhyticlicolus in S. America. Of the above mentioned groups, that of the Nemesiae is the only one that is represented at the present time in India, Madagascar, and New Zealand-a fact in keeping with its primitive status, and suggestive of an earlier migration into the Southern hemispheres. Singularly enough, the group is unrepresented in North America. This and the further facts that South Africa is the richest of the regions in number of genera, and that one of its genera, Hermacha, occurs also in Brazil, make it almost impossible to doubt that the group entered South America from South Africa. Again, since the group is also apparently absent from the whole of the area lying between India and Australia, we must look to South Africa, Madagascar, or South America as the source whence it entered Australia; and since the Mascarene genus Genysa is said to be nearly allied to the Australian Arbanitis, Madagascar and S. Africa were perhaps the feeders to the Australian area. Since the Cyrtauclienii are specialised allies of the Nemesise, and therefore later developed forms, it is interesting to note their apparent absence from Madagascar, India, Australia, and New Zealand, which indicates a later southern migration from the north. The following hypothesis seems to explain the facts of their distribution. In early Tertiary times the group was continuously distributed throughout Europe, Asia, and North America. In Eastern Asia it descended a short distance into Indo-Malaya after the severance of Australia, and penetrated Africa after the forma tion of the Mozambique Channel. Similarly from the Sonoran Region it passed into Central and South America, after the Pliocene union of the latter with North America, Whether 'any of the South-American fauna was derived from Africa or vice versd, there is no reliable evidence to show. If the Aganippse entered Australia from South-eastern Asia, it is strange that no related forms have been discovered in Austro- Malaysia. They may have come from South America or South Africa; but I am disposed to think that they have had an origin independent of the Cyrtauchenii in Australia from the Nemesise, from which they differ practically only in the procurvature of the fovea-a feature which is known to have arisen more than once |
