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Show 1881.] REV. O. P. CAMBRIDGE ON NEW ARANEIDEA. 765 This animal is met with on the western borders of Griqualand West, and all along the eastern edge of the Kalahari desert, and all over south Central Africa wherever I have travelled from the Limpopo to the Zambesi; and from the Mashuna country to Lake Ngami it is to be found in those districts that are suitable to its habits. Like the Tsessebe it is partial to open downs devoid of bush, or open glades in the forest, and is never met with in hilly countries. On the Mababe flat it congregates in immense herds during the dry season. In the Manica country, north of the Zambesi, I did not see any Blue Wildebeest; but the natives told me that to the west of the river Kafukwe, in the country of the Mashukulumbwe, they were plentiful. The horns of the males attain a spread of from 2 feet 2 inches to 2 feet 5 inches. It is very common to see one Blue Wildebeest feeding in company with a herd of other Antelopes, such as the Tsessebe, or with a herd of Zebras or Ostriches. The Blue Wildebeest is very swift and enduring. 5. On some new Genera and Species of Araneidea. By the Rev. O. P. CAMBRIDGE, M.A. &C. [Received June 7, 1881.] (Plate LXVI.) Six Spiders only are described in the present short paper-four of them from the Amazons, one from Ceylon, and one from Madagascar. They have not been designedly selected for the purpose ; but, as it happens, two of them represent, perhaps, the most extreme known instances of eccentric development-one of the caput, the other of the aBdomen. It is difficult to imagine any possible utility to the Spider in such developments, while it is not so difficult to conjecture some disadvantages. This, however, in the absence of information as to the life and habits of the Spiders, is, of course, mere conjecture. The development of aBdomen referred to is in Ariamnes attenuata, sp. n. In this Spider the posterior extremity of the abdomen of the male is produced to an extent of very nearly (if not quite) eight times its normal length. That of the female is also much produced, but not to so great an extent. In the other instance, the caput of Eriauchenus workmanni (gen. et sp. nn.) is not only elevated to an almost unprecedented height, but it furnishes the only instance known to me in which the elevation of the ocular area (of itself not an unusual occurrence in the Araneidea) has, as it were, carried up with it the lower margin of the caput, and so necessitated a corresponding development in the length of the falces. Of the remaining Spiders, Thwaitesia margaritifera (gen. et sp. nn.) is one of exceedingly delicate beauty, the silvery pearl-like scales on its abdomen forming a most beautiful object for the microscope ; and Bucranium taurifrons (gen. et sp. nn.) has enabled me to fix (I think, without doubt) the hitherto doubtful systematic position of |