1881.] RICV. 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. Li 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 Masliuknlumbwe, 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 Wilde- 

 beest feeding in company with a herd of other Antelopes, such as the 

 Tsessebe, or with a herd of Zebras or Ostriches. The Blue Wilde- 

 beest is very swift and enduring. 



5. On some new Genera and Species of Araneidea. By the 

 Rev. O. P. Cambridge, M.A. &e. 



[Eeceived June 7, 1881.] 



(Plate LXVL) 



Six Spiders only are described in the present short paper — four 

 of them from the Amazons, one from Ceylon, and one from ]Ma- 

 dagascar. They have not been designedly selected for the pur- 

 pose ; 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 pos- 

 sible 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 attenuuta, sp. n. In this Spider the posterior ex- 

 tremity 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 Eriuiichenus workmanni (gen. et sp. nn.) 

 is not only elevated to an almost unprecedented height, but it fur- 

 nishes 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 tauri/rons (gen. et sp. nn.) has enabled me to fix (I 

 think, without doubt) the hitherto doubtful systematic position of 



